Method and apparatus for sodding microvessel cells onto a synthetic vascular graft

An apparatus for sodding onto the inner lumenal surface of a synthetic graft of harvested and concentrated microvessel endothelial cells from liposuctioned fat tissues, which harvested cells are formed into a "pellet" of isolated endothelial cells in loose aggregations, includes a sodding tube having a single rigid outer wall bounding a sodding chamber. A filter pack assembly is provided to communicate the pellet of cells from a processing vessel to the graft. This filter pack assembly includes a series of successively finer filter members cooperatively defining a series of turbulent-flow chambers in which aggregations of cells too large to pass through a particular filter are exposed to liquid flow turbulence which is effective to break up the aggregations. A check valve assembly ensures that liquid flow is unidirectional so that sodding of the cells onto the inner lumenal surface of the graft is not interfered with by possible liquid reflux, and sodded cells are similarly not dislodged from the graft by such liquid reflux.

CROSS REFERENCE TO RELATED APPLICATION 
The present application discloses subject matter which is related to that 
of U.S. patent applications Ser. No. 08/086,778, filed Jul. 1, 1993, now 
U.S. Pat. No. 5,409,833; and Ser. No. 08/647,155 filed May 9, 1996, and 
currently pending; both of which are assigned to the assignee of this 
application. 
BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention is in the field of vascular grafting. More 
particularly, the present invention relates to methods and apparatus for 
isolation of microvessel cells (generally referred to as endothelial 
cells) from a patient who is to receive a synthetic graft, which graft has 
a porous inner lumenal surface; and for sodding of the endothelial cells 
onto this inner lumenal surface of the graft. Deposition of the 
endothelial cells onto and into the porous inner lumenal surface of the 
graft is an effective method of reducing or eliminating the formation of 
post-graft clots (thrombogenicity) on the lumenal surface of the graft. 
Thus, the occurrence of thrombosis of and emboli in the circulatory system 
of the patient, which result from blockage of the graft by or sloughing 
off of such post-graft clots from this inner lumenal surface, is also 
reduced or eliminated (i.e., thrombogenicity is reduced) by the present 
invention. 
2. Related Technology 
A conventional technology for treating a synthetic or naturally occurring 
surface with microvessel endothelial cells is set forth in U.S. Pat. No. 
4,820,626, issued Apr. 11, 1989 to Stuart K. Williams et al. In summary, 
the teaching of this Williams patent is to obtain tissues rich in 
microvessel endothelial cells, to separate the endothelial cells from the 
other tissues, and to place these cells onto the inner lumenal surface of 
the graft. 
The methodology disclosed by the Williams patent is both labor and skill 
intensive to carry out. Accordingly, the results obtained vary from time 
to time and are dependent upon the training, skill, and attention of the 
technician who performs the procedure. Also, the procedure is expensive 
because of the labor intensive methodology used and the requirement for a 
highly skilled person to perform the procedure. 
Recently, technologies for the harvesting, separation, isolation, 
culturing, and deposition onto a synthetic vascular graft of microvessel 
endothelial cells have progressed somewhat beyond the labor and skill 
intensive laboratory methods initially used. Consequently, the 
time-consuming methods which were initially used to prove the efficacy of 
this technology for reducing the thrombogenicity of synthetic vascular 
grafts are now practiced with apparatus making the procedure less time 
consuming, less prone to error, more sterile, and safer for the patient 
and medical personnel. 
Further to the above, a conventional apparatus and method for preparing a 
synthetic vascular graft with a lumenal lining of endothelial cells taken 
by liposuction from the patient who is to receive the graft is known in 
accord with U.S. Pat. No. 5,035,708, issued Jul. 30, 1991, to Paul G. 
Alchas et al. According to the Alchas patent, an endothelial cell 
isolation device includes a primary chamber tapering downwardly to a 
secondary chamber or ampule. The secondary chamber also has an upper inlet 
port and a lower outlet port communicating outwardly of the cell isolation 
device. Digested fat tissue slurry, with microvessel endothelial cells 
therein, is introduced into the upper primary chamber, and the isolation 
device is centrifuged at about 700G for about 7 minutes to produce an 
endothelial cell product in the form of a "pellet" composed essentially of 
endothelial cells. This pellet of endothelial cells is then isolated from 
the fat cells and red blood cells also in the chamber of the isolation 
device, and is transferred from the cell isolation device to a cell 
deposition apparatus. 
The cell deposition apparatus of the '708 Alchas patent is believed to 
assert that dispersal of the endothelial cells in a solution of autologous 
serum and media is effected. From this suspension, the endothelial cells 
are deposited onto and into the porous inner lumenal surface of a 
synthetic vascular graft. The cell deposition device includes both an 
inner and an outer tube. Within the outer tube, a rotator apparatus is 
arranged to rotate the inner tube along its axis. Rotary fluid fittings 
are required at each end of the inner tube to allow the microvessel cells 
in suspension to flow into the rotational inner tube where the graft is 
located. A heating pad is also located within the outer tube and around 
the inner tube to effect temperature stabilization of the graft during 
sodding of the endothelial cells onto the inner lumenal surface of the 
graft. A vortex/mesh assembly is asserted to break up the endothelial cell 
pellet and to filter out gross particulates. The endothelial cells are 
asserted to be re-suspended in autologous serum/media solution and to be 
drawn onto the inner luminal surface of the graft by vacuum. 
However, experience has shown the devices and methods according to the 
conventional technology are overly complex in their structure and are 
difficult to use. The results obtained with these conventional devices is 
not as good as could be hoped for. That is, the pellet of endothelial 
cells is not as effectively broken up and the cells are not as effectively 
re-suspended in the solution of serum and/or media in preparation for 
sodding onto the graft as would be necessary to achieve best utilization 
of the available cells. Clumps and aggregations of the endothelial cells 
which are not broken up are trapped before delivery to the graft, or are 
flushed from the graft with little or no effective sodding of the cells 
forming these clumps onto the inner lumenal surface of the graft. In fact, 
a significant deficiency in the apparatus according to the '708 Alchas 
patent derives from its use of a static mixer as the principle component 
of the vortex/mesh assembly. Such static mixers are generally used to mix 
two or more fluid streams which are introduced simultaneously into one end 
of a single flow path an individual fluid streams. The static mixer is 
disposed along the length of this single flow path and repeatedly divides 
and recombines portions of the individual flow streams until a homogeneous 
single flow of liquid is achieved. These static mixers achieve homogeneity 
of the fluid stream by repeatedly dividing and re-combining different 
sub-parts of a fluid stream. When used to mix such viscous fluids as the 
two parts of an epoxy adhesive, these static mixers do a good job of 
mixing together the two parts of the epoxy. However, such mixers are not 
intended to and do not do an effective job of breaking up a pellet or 
aggregation of solids (such as micro-vessel cells) suspended in a liquid 
of comparatively low viscosity. 
Moreover, with the devices and methods of the conventional technology, the 
complexity of the structures and methods employed are compounded both by 
an inefficiency in the separation of the microvessel endothelial cells 
from the fat cells in the slurry (meaning that a low yield of endothelial 
cells is provided with which to do the cell deposition onto the inner 
lumenal surface of the synthetic graft), and with an inefficiency in the 
utilization of the harvested cells by the cell deposition apparatus. As a 
result, many microvessel endothelial cells which are present in the fat 
slurry are simply not recovered or are thrown away with the disposable 
deposition device without being sodded onto the graft. Consequently, the 
patient may have to endure a more extensive liposuction than otherwise 
would be required in order to provide a sufficient number of endothelial 
cells. While a graft sodded with any level of cells is preferable to an 
unsodded graft because the former is less thrombogenic, a graft which is 
more thrombogenic than desired may result with the conventional technology 
because grafts so sodded may still have an insufficient level of sodding 
of endothelial cells on their inner lumenal surface. 
More particularly, the cell deposition apparatus is believed to be 
generally ineffective in providing a uniform dispersal of the endothelial 
cells into the autologous serum and media. Consequently, cells are damaged 
by the deposition apparatus, or are rendered as a dispersion which 
includes many comparatively large clumps or aggregations of cells. The 
damaged cells are not as fully advantageous for deposition on the inner 
surface of a graft as are healthy, undamaged and viable cells, and the 
clumps or aggregations of cells will not deposit effectively on the graft 
surface or will be trapped in the deposition apparatus. That is, such 
aggregations of cells effectively prevents dispersal of large numbers of 
the available cells over the surface of the graft, and also will generally 
be flushed away entirely by flushing of the graft before surgical 
placement, or by blood flow after surgical placement of the graft. 
Yet another conventional apparatus is known in accord with U.S. Pat. No. 
5,171,261, issued Dec. 15, 1992 to Y. Noishiki et al. The teaching of the 
'261 Noishiki patent is believed to be to treat a synthetic vascular graft 
with tissue fragments or cells, for example, which fragments and cells are 
entangled into the pores of the porous and fibrous vascular graft. In 
order to effect this entanglement of the cells and tissue fragments into 
the pores of the synthetic vascular graft, the graft is placed within a 
flexible bag, and a perforate tube is placed within the graft. A syringe 
is connected to the inner tube and a separate tube leads from the space 
between the graft and outer bag to an external vacuum or pressure source 
so that fluid pressure can be maintained radially across the graft. With 
this arrangement the tissue fragments and cells in liquid suspension can 
be instilled into the pores of the graft. Noishiki does not appear to 
teach any particular means or method for dealing with the problem of the 
harvested cells clumping and not depositing effectively on the inner 
lumenal surface of a graft. Moreover, the apparatus and method disclosed 
by the '261 Noishiki patent appear to still represent a laboratory-like 
contrivance of structure and components which will rely heavily upon the 
skill of a technician for successful practice of the procedure. 
However, a need exists to improve and simplify the apparatus and methods 
used to sod endothelial cells onto the inner lumenal surface of a 
synthetic vascular graft. That is, a need exists for apparatus and methods 
which are simple in structure and uncomplicated in their execution, and 
which provide a favorable consistent result and are not labor or skill 
intensive. Additionally, a need exists to improve the safety, efficiency 
in terms of time and skills required and in terms of yield of microvessel 
cells available for deposition on the graft, manufacturability, and user 
convenience of the available apparatus for sodding endothelial microvessel 
cells for use on the vascular graft. In other words, the entire procedure 
of sodding microvessel endothelial cells in preparation for surgical 
grafting should be made less of a laboratory-like procedure requiring 
highly skilled personnel, make-shift apparatus, and considerable time 
delays; and into a procedure which can be accomplished with little 
specialized training, in a short time while the graft implantation surgery 
is underway, and with high sterility and safety for both the patient and 
the surgical personnel. 
SUMMARY OF THE INVENTION 
In view of the deficiencies of the related technology as outlined above, a 
primary object for this invention is to overcome one or more of these 
deficiencies of the conventional technology. 
Another object is to improve the yield or recovery rate of viable 
microvessel endothelial cells from a pellet of epithelial cells prepared 
from digested fat slurry preparatory to deposition of these cells on a 
synthetic vascular graft. 
Another object for the present invention is to improve the 
manufacturability of an endothelial cell sodding apparatus for use in 
placing microvessel endothelial cells on the inner lumenal surface of a 
synthetic graft as outlined above. 
Still another object for the present invention is to improve the protection 
afforded to medical personnel with respect to avoiding exposure to 
blood-borne infectious agents; 
Another objective of the present invention is to improve the ease of 
manufacture for a cell sodding apparatus by considerably simplifying its 
structure while also improving the performance of this apparatus in 
comparison to conventional technologies. 
Accordingly, the present invention provides a sodding tube assembly 
particularly adapted for receiving endothelial microvessel cells and other 
materials, such as a quantity of certain identified and isolated cells 
from tissues, and for sodding these cells or other materials onto an inner 
lumenal surface of a tubular synthetic graft having a porous wall, the 
sodding tube assembly including an elongate semi-rigid and shape-retaining 
tubular member having a pair of opposite ends; an inlet fitting and filter 
pack assembly sealingly cooperating with the tubular member at one of the 
pair of opposite ends, the inlet and filter pack assembly including flow 
path means for receiving the quantity of cells in liquid and communicating 
the cells and liquid into the lumen of the graft, and means for defining a 
plurality of turbulent-flow chambers along the flow path means, the means 
for defining a plurality of turbulent-flow chambers including a plurality 
of filter members interposed between adjacent ones of the plurality of 
turbulent-flow chambers; and an outlet fitting and check valve assembly 
sealingly cooperating with the tubular member at the other of the pair of 
opposite ends, the inlet and filter pack assembly and the outlet and check 
valve assembly cooperating with the tubular member to define a sodding 
chamber within which the graft is disposed to receive the cells and liquid 
from the inlet and filter pack assembly into the lumen of the graft and to 
flow the liquid outwardly through the porous wall of the graft to the 
sodding chamber, the outlet fitting and check valve assembly defining flow 
path means leading from the sodding chamber to an outlet from the sodding 
tube assembly, and including check valve means disposed in the flow path 
of the outlet fitting and check valve assembly for preventing reflux of 
liquid along the flow path from the outlet toward said sodding chamber. 
Additional objects and advantages of the present invention will be apparent 
from a reading of the following detailed description of an exemplary 
preferred embodiment of the invention taken in conjunction with the 
appended drawing figures in which like reference numerals denote the same 
features or features which are analogous in structure.

DETAILED DESCRIPTION OF THE PREFERRED EXEMPLARY EMBODIMENT 
As those ordinarily skilled in the pertinent arts will appreciate, the 
current technology teaches to harvest tissue which is rich in 
microvessels, and to separate these microvessel cells from the remainder 
of the harvested tissue. The separated microvessel endothelial cells are 
then collected into a "pellet" of such cells by centrifuging a vessel in 
which the cells have been separated from other collected tissues. The 
microvessel cells are then used for lining a vascular graft, and the graft 
is surgically implanted into a patient who donated the tissue. This 
procedure provides a remarkably reduced thrombogenicity for the synthetic 
vascular grafts. The donated microvessel endothelial cells are recognized 
by the body of the patient as "self", so that initial acceptance of the 
graft into the patient's circulatory system without adverse reactions, as 
well as the construction of new vascular tissues on the graft are 
improved. 
The present technology teaches to harvest adipose or fat tissues from the 
patient, usually by use of liposuction, and to digest these fat tissues 
with an enzyme to free the microvessel cells. The microvessel cells are 
then separated from the fat cells by straining and centrifuging to form 
the pellet of these cells. The pellet of cells is then transferred to a 
cell deposition apparatus, is broken up to individual cells while 
preventing so far as is possible damage to the cells, and the cells are 
deposited on the inner lumenal surface of the vascular graft. The 
complexity of the present technology combined with its inefficient 
separating of the pellet of cells is outlined above. The present invention 
provides a much simplified apparatus which is at the same time more 
effective in achieving separation of the cell pellet into individual cells 
and sodding of these cells onto the inner lumenal surface of a graft. 
Viewing FIG. 1, an apparatus 10 for sodding harvested microvessel cells 
onto the inner lumenal surface of an elongate tubular synthetic vascular 
graft 12 is depicted. The graft 12 (only a small portion of which is 
visible in FIG. 1) is disposed within a similarly elongate tubular sodding 
tube 14. Further, the apparatus 10 is connected by a flexible conduit 16 
to a processing vessel assembly 18. This processing vessel assembly 18 
includes a processing vessel 20, and a holder 22 for the processing vessel 
20. Closer examination of the processing vessel 20 will show that it 
includes a chambered upper tissue digestion and separation portion, 
generally indicated with the numeral 24; and a lower chambered collection 
structure (referred to as an ampule chamber portion), and generally 
indicated with the numeral 26. Within this ampule chamber portion 26, 
microvessel endothelial cells which have been separated from endothelial 
or adipose cells by enzymatic digestion are concentrated by centrifuging 
into an elongate vertically extending passage (not seen in the drawing 
Figures) to form a "pellet" of such cells. 
A pair of manually-operable two-way valving members 28 and 30 are carried 
on the ampule portion 26. The upper one 28 of these two valving members 
(dependent upon its rotational position) respectively connects the 
internal passage of the ampule portion 26 at its upper end either to the 
digestion and separation portion 24 or to a respective luer-type fitting, 
which fitting is disposed on the back side of the ampule portion 26 as 
seen in FIG. 1 and is only partially visible in this Figure. In order to 
provide for flushing of the pellet of endothelial cells from the ampule 
portion 26, this top luer-type fitting is connected to a source of liquid, 
such as a solution of serum and/or media (not shown). The lower valve 
member 30 selectively connects the inner passage of the ampule portion 26 
at a location slightly above the lower end of this passage to a luer-type 
fitting 32. The conduit 16 is connected with the fitting 32 in order to 
receive the pellet of centrifuged microvessel endothelial cells from the 
ampule portion 26. Those ordinarily skilled in the pertinent arts will 
recognize that the positions of the conduit 16 and of the connection to 
the source of liquid may optionally be reversed. 
By a flow of liquid through the ampule portion 26 and into the conduit 16, 
as is indicated by the arrow 34, the pellet of microvessel endothelial 
cells is flushed through the conduit 16 and to the sodding tube 14. The 
sodding tube 14 includes a luer-type fitting 36, to which the conduit 16 
is also connected. Viewing FIGS. 1 and 3 in conjunction, it is seen that 
the conduit 16 at each end includes a male luer-type fitting 38 with a 
freely-rotational collar portion so that the conduit 16 may be connected 
with the fittings 32 and 36 without twisting of this conduit or relative 
rotation of either of the assembly 18 or of tube 14. This feature provides 
a considerable convenience and ease of handling of the apparatus 10 under 
operating room conditions. 
The sodding tube 14 includes an inlet and filter pack portion, generally 
indicated with the numeral 40, an elongate sodding chamber tube portion 
42, and an outlet fitting and check valve portion 44. Portion 44 provides 
fluid connection via a conduit 46, and as is indicated by arrow 48, for 
fluid flow from the graft 12 within tube portion 42 to a liquid catch 
receptacle 50. Receptacle 50 may be connected to a source of vacuum, as is 
indicated by arrow 52. 
Viewing FIGS. 2 and 3 more particularly, it is seen that the sodding tube 
chamber portion 42 of sodding tube 14 includes an elongate semi-rigid and 
shape-retaining tubular member 54, which cooperates with the inlet fitting 
portion and with outlet fitting portion 44 to define a sodding chamber 56. 
Graft 12 is extended along the length of chamber 56, as will be more fully 
explained below. Adjacent to each end, the sodding tube member 54 defines 
a radially outwardly opening groove, both of which are referenced with the 
numeral 58. Both ends of the sodding tube member 54 are the same so that 
this tubular member is reversible and the sodding tube 14 may be assembled 
without concern for which end of the tube 42 is assembled with the inlet 
or outlet end fittings. An O-type sealing ring member 60 is received into 
each groove 58. 
The inlet and filter pack fitting portion 40 includes an elongate tubular 
body 62 defining an axially extending stepped through bore 64. A smaller 
diameter portion 66 of bore 64 opens axially on a dual-size hose barb 68. 
Barb 68 outwardly has a first section 68', upon which graft 12 is 
received, which is sized to sealingly receive such a 4 mm. graft. A second 
and outwardly larger diameter section 68" of the barb 68 may sealingly 
receive a 5 mm. graft (not shown). Those ordinarily skilled in the 
pertinent arts will recognize that the 4 mm. and 5 mm. sizes shown are 
merely representative, and that the invention may be used to sod grafts of 
various sizes with cells by providing components of appropriated physical 
size. An elastic ring 69 is received on the barb 68 and around the 
proximal end portion of graft 12. This elastic ring 69 is similar to an 
O-ring, and may be slid along the graft onto the barb 68, subsequently to 
be rolled along the barb 68 to secure either size of graft on this barb. 
A larger diameter portion 70 of the stepped bore 64 receives a filter pack 
assembly, which is generally referenced with the numeral 72. The filter 
pack assembly 72 includes four disk-like screen filter members, 
respectively referenced with the numerals 74a, 74b, 74c, and 74d. These 
screen filter members 74a-d are successively of finer mesh toward the 
sodding chamber 56, and are spaced apart from one another by intervening 
tubular spacer sleeve members 76a, 76b, and 76c. Preferably, the filter 
member 74a is a square weave of 0.0160 inch stainless steel wire, with a 
mesh of 20.times.20 wires, providing openings of substantially 0.0340 inch 
square, with an open area of 46.2 percent. Preferably, the filter member 
74b is a square weave of 0.0085 inch stainless steel wire, with a mesh of 
40.times.40 wires, providing openings of substantially 0.0165 inch square, 
with an open area of 43.6 percent. Filter member 74c is preferably a 
square weave of 0.0035 inch stainless steel wire, with a mesh of 
88.times.88 wires, providing openings of substantially 0.0079 inch square, 
with an open area of 47.9 percent. Finally, filter member 74d is 
preferably a square weave of 0.0011 inch stainless steel wire, with a mesh 
of 325.times.325 wires, providing openings of substantially 0.0020 inch 
square, with an open area of 41.6 percent. Consequently, it is apparent 
that cell aggregations larger than the openings of the filter member 74d 
cannot pass to the graft 12. Understandably, individual cells and smaller 
aggregations of cells pass through the filters 74a-d, and into the lumen 
of the graft 12. Importantly, the open area of each filter member 74a-d is 
similar, and the fluid flow resistance of these filter members is also 
similar. Consequently, a selected and controlled level of turbulence is 
achieved both upstream and downstream of each of the filter members 74a-d. 
Those ordinarily skilled in the pertinent arts will recognize that the 
stainless steel wire of the screens 74a-d is preferably coated with 
parylene in order to lower the surface energy of the surface exposed to 
the viable cells. Alternatively, as a substitute for metallic screens 74, 
screen or mesh material of appropriate filament size to provide the 
necessary opening sizes and open areas, and formed of polymer material 
which has sufficient mechanical strength to sustain the pressure 
differential across these filter members may be used in the filter pack 
assembly 72. 
The screen filter member 74d rests upon a step 78 on bore 64, while the 
screen member 74a is engaged by a closure member 80 defining a recess 82 
confronting the screen member 74a. Consequently, a series of chambers 84a, 
84b, 84c, 84d, and 84e each successively closer to the sodding chamber 56 
are defined within the tubular body 62. This tubular body 62 outwardly 
defines a thread portion 86 upon which a tubular nut member 88 is 
threadably engageable. This nut member 88 traps an O-ring type sealing 
member 90, while the closure member 80 includes a cylindrical portion 92 
upon which a groove 94 is defined. An O-ring type of sealing member 96 is 
received into the groove 94, and sealingly cooperates with the inner 
surface of the tubular body 62. Thus, redundant sealing is provided at the 
interface of the closure member 80 and tubular body 62 to assure that 
blood products are not lost into the environment where surgical and 
laboratory personnel are working with the apparatus 10. 
The luer fitting 36 is threadably received at an end of a stepped through 
bore 98, a larger diameter portion of which defines the recess 82. In 
order to secure the tubular body 62 sealingly to the sodding chamber 
tubular member 54, the body 62 outwardly defines a thread portion 100 
leading to a cylindrical portion 102. The cylindrical portion 102 is sized 
to fit closely within the tubular member 54. A nut member 104 is 
threadably received upon the thread portion 100, and defines a stepped 
bore 106. The O-ring member 60 is trapped in a portion 108 of the bore 106 
when the nut member 104 is threadably engaged with thread portion 100 with 
the cylindrical portion 102 inserted into the tubular member 54, viewing 
FIG. 3. 
Returning for a moment to a consideration of FIG. 1, is seen that the graft 
12 is disposed within and along the length of the tubular member 54. One 
end of the graft is sealingly secured to the dual-size barb 68. A portion 
of the tubular member 54 is broken away in FIG. 1 solely for purposes of 
illustration to reveal that a proximal end of the graft 12 is closed by a 
barbed and dual-size plug member 110. Similarly to the barb 68, an elastic 
ring 69 secures the plug member 110 in the distal end portion of graft 12. 
Thus, it will be appreciated that the liquid introduced into the graft is 
forced to flow through the porous wall of this graft. However, the graft 
acts as a filter with respect the microvessel endothelial cells, so that 
these cells are deposited onto and into the inner lumenal surface of the 
graft 12. 
Attention now to FIG. 4 will show that the outlet and check valve fitting 
portion 44 includes a tubular body 112. Similarly to the tubular body 62, 
this body 112, includes a cylindrical portion 114 sized to fit within the 
tubular body 54, and a thread portion 116. A nut member 118 threadably 
engages the thread portion 116 and forces the O-ring 60 sealingly into a 
portion 120 of a stepped bore 122 of this nut member 118. The tubular 
member 112 defines a through bore 124, an outer portion of which is 
threaded. A male luer-type fitting 126 is threadably and sealingly 
received into the bore 124, and provides for a check valve assembly 128 to 
be connected with the bore 124. This check valve assembly 128 includes a 
tubular body 130 defining a stepped through bore 132. The bore 132 
terminates in a hose barb portion 134 to which the conduit 46 is 
connected. Within bore 132 is sealingly disposed a resilient polymeric 
duck-bill type valve body 136. This valve body 136 includes a pair of 
mutually engaging and cooperating pressure-responsive lips or "duck bill" 
portions 138 which sealingly cooperate with one another to prevent fluid 
flow from conduit 46 toward chamber 56, but which will yieldably disengage 
from one another to allow fluid flow in the opposite direction. 
Having considered the structure of the apparatus illustrated in FIGS. 1-4, 
attention may now be directed to their use and function. As those 
ordinarily skilled in the pertinent arts will know, adipose or fat tissue, 
which is rich in microvessel cells, is harvested from a patient who is to 
receive a synthetic vascular graft. This harvesting may preferably be 
conducted by use of a liposuction apparatus (not shown). Most preferably, 
the tissue harvesting may be conducted using an apparatus as disclosed in 
U.S. patent application Ser. No. 08/647,155, which was identified above, 
and the disclosure of which is hereby incorporated by reference as though 
it were fully set out. The harvested fat tissue immediately from the body 
and while still warm is injected via a port on the top of the process 
vessel 20 into a chamber defined within the upper portion 24 of the 
process vessel so that this tissue resides within a screen basket assembly 
(not shown) held within this vessel. The harvested fat tissue is then 
rinsed with sterile liquid to remove most of the connective tissue and 
blood cells which have been collected by the liposuction process. 
Next, an enzymatic digesting material, such as collagenase, which is also 
warmed to body temperature is introduced into the upper chamber of portion 
24. The process vessel 20, which is already in its holder 22, is placed 
into a protective outer canister (not shown), and this canister is closed 
with a lid (also not shown). This process vessel assembly with the rinsed 
fat tissues and enzymatic digestion material is placed into a warm air 
oven upon an agitation plate. The warm air oven serves to preserve the 
tissues at about body temperature, and to facilitate digestion with the 
enzymatic material to free the microvessel cells. This digestion and 
freeing of the microvessel cells is assisted by agitation. 
Directly from the warm air oven and agitation, the process vessel assembly 
18 is transferred to a centrifuge. Again at this stage of the process, the 
holder 22 and closed canister (not shown) serve to prevent spilling of the 
contents of the process vessel 20, and to protect medical personnel from 
contact with patient tissues and body fluids. Preferably, this process is 
carried out in accord with the teaching of U.S. patent application Ser. 
No. 08/086,778, identified above, now U.S. Pat. No. 5,409,833, and the 
disclosure of which is hereby incorporated by reference as though it were 
fully set out. The centrifuge is operated at about 700 Gs for a time 
sufficient to separate the freed microvessel cells from the fat cells in 
the chamber within upper portion 24. During this centrifuging operation, 
the valving members 28 and 30 are in the positions necessary to 
communicate the upper chamber of the process vessel 20 with the ampule 
chamber within lower portion 26. Consequently, a "pellet" of microvessel 
cells is formed in the ampule chamber portion 26. A small residue of 
packed red blood cells and other solid debris may be formed in the very 
bottom of the ampule chamber portion 26. 
After the process vessel assembly 18 is removed from the centrifuge, the 
vessel 20 in its holder 22 is removed from the canister (not shown), and 
placed in association with the sodding tube 14 containing the synthetic 
graft 12 which the patient is to receive. This sodding tube 14 may 
preferably be supplied as a sterile assembly including the graft 12 
already in sodding chamber 56. The sterile sodding tube and graft are 
removed from their sterile shipping package immediately prior to 
connection of the conduits 16 and 46 in order to assist in best preserving 
aseptic conditions for the sodding process. 
In order to transfer the pellet of microvessel cells from the ampule 
chamber portion 26 of the process vessel 20 to the sodding tube 14, a 
source of sterile buffered liquid at about body temperature is connected 
to the luer fitting associated with valve member 28. This source of liquid 
may be elevated somewhat to assist in the necessary liquid flow. The valve 
member 28 is moved to the position communicating the liquid into the upper 
end of the ampule chamber portion 26, which simultaneously separates the 
ampule portion 26 from the processing chamber portion 24. The luer fitting 
32 is connected to the sodding tube 14 by conduit 16, and the valve member 
30 is manually turned to the position communicating the ampule chamber 
portion with the fitting 32. Turning the valve member 30 in this way also 
separates the small quantity of packed red blood cells and other debris 
which collects in the bottom of the passage of the ampule chamber portion 
26 from communication with luer fitting 32. Additionally, the sodding tube 
14 is evacuated so that a partial vacuum assists in pulling liquid from 
the source through the ampule chamber portion 26, through the conduit 16, 
through the filter pack portion 40, and into the inner lumen of the graft 
12. As described above, the liquid is then forced to flow through the 
porous wall of the graft 12 so that the microvessel endothelial cells are 
deposited onto and into the porous surface of this graft 12. 
Consideration of FIG. 3 once again will reveal (as is indicated by the 
fluid flow arrows on this figure) that a selected and controlled level of 
fluid flow and turbulence is maintained in each one of the chambers 84a-e 
by the filter members 74a-d. This level of fluid flow and turbulence is 
selected to effectively break up the pellet of microvessel endothelial 
cells into individual cells and successively smaller aggregations of 
cells. That is, the pellet of cells initially may be considered as a loose 
aggregation of cells, which when broken up forms individual cells loose in 
the liquid medium and a multitude of smaller aggregations of cells of 
various sizes. The individual cells flow freely downstream into the lumen 
of the graft 12 in sodding chamber 54. Aggregations of cells which are 
small enough to pass through the filter 74a may or may not pass through 
filter 74b, and so on with the following filters 74c and 74d. Aggregations 
of cells which are not small enough to pass through a particular filter 
will be exposed to the turbulence and a gentle "buffeting" because of the 
selected level of fluid flow maintained in the chambers 84a-e. The level 
of turbulence and fluid flow is balanced so that cells are not excessively 
damaged by impacts with the filter members, and are not lodged into the 
interstices of the filter members 74a-d. Consequently, the larger 
aggregations in each chamber 84a-d are successively broken up into 
progressively smaller aggregations, freeing individual cells and smaller 
aggregations with each successive break up of larger aggregations. By this 
process, a high yield of viable microvessel endothelial cells is provided 
for sodding onto the inner lumenal surface of the graft 12. The check 
valve assembly 128 prevents any possible reflux of liquid which could 
interfere with sodding of cells onto the surface of the graft 12. 
Construction and testing of actual apparatus 10 for sodding harvested 
microvessel cells, and use of this apparatus to sod cells onto the inner 
lumenal surface of grafts 12 in accord with the present invention has 
shown a remarkable improvement in the yield of microvessel cells per gram 
of fat tissue processed. Consequently, the reduction in thrombogenicity of 
a synthetic graft which can be effected by lining the graft with 
microvessel cells from the patient can be improved by use of the present 
invention. Also, the efficacious number of microvessel cells necessary to 
treat a synthetic graft may be obtained with a smaller extraction of 
adipose tissue from the patient. 
FIGS. 5-7 provide representations of microphotographs of microvessel cells 
sodded onto the inner lumenal surface of a graft at three locations along 
the length of the graft, as is evidenced by photographs of the stained 
cell nucleus (indicated with the representative reference numeral 140) 
taken while the stained cells were illuminated with ultraviolet light. 
These depictions of the microphotographs indicate that a more than 
adequate level of cell sodding is present on the inner lumenal surface of 
the graft 12. FIG. 5 is a depiction of an area of the graft slightly 
distally of the barb 68. FIG. 6 is taken at mid-length of the graft 12. 
FIG. 7 represents a microphotograph taken just proximally of the plug 
member 110, recalling FIG. 1. These Figures illustrate the uniform 
distribution of the isolated cells on the inner surface of the graft 12. 
Thus, it is seen that all or a selected portion of the graft 12 may be 
surgically implanted with the graft providing a low thrombogenicity 
because of the sodded cells on the inner lumenal surface of this graft. 
While the present invention has been depicted, described, and is defined by 
reference to a particularly preferred embodiment of the invention, such 
reference does not imply a limitation on the invention, and no such 
limitation is to be inferred. The invention is capable of considerable 
modification, alteration, and equivalents in form and function, as will 
occur to those ordinarily skilled in the pertinent arts. The depicted and 
described preferred embodiment of the invention is exemplary only, and is 
not exhaustive of the scope of the invention. Consequently, the invention 
is intended to be limited only by the spirit and scope of the appended 
claims, giving full cognizance to equivalents in all respects.