Patent Application: US-201313969553-A

Abstract:
a device including a pressure generating assembly and a chamber for generating hydrostatic pressure in the said chamber . in particular , the device is useful for cell mechanical stimulation and tissue regeneration by generating hydrostatic pressure in a chamber receiving samples such as cell cultures , biological tissues , and cell seeded biomaterial constructs for the purpose of treatment with hydrostatic pressure . the pressure generating assembly of the device comprises a piston and a cylinder generating and relieving pressure by moving the piston in the cylinder using an actuating system for quick placement and removal of the piston in and out of the cylinder . the device is portable and autoclavable and can be hand operated without any tool to generate pressures at high physiological levels up to at least 10 mpa . the device has a venting system allowing vital gasses to reach the samples under treatment when the device is placed in an incubator .

Description:
the invention will now be described in detail with reference to the accompanying drawings . fig1 and 2 , show a hydrostatic pressure generator device 10 according to an embodiment of the present invention . as hereinafter described , the hydrostatic pressure generator device 10 is operated between a pressurizing position and a retracting or venting position . the pressurizing position is shown in fig1 and the venting position is shown in fig2 . in accordance with a preferred embodiment illustrated in fig1 and 2 , hereinafter referred to as the first embodiment , the hydrostatic pressure generator device 10 comprises a pressure generating assembly 12 and a chamber 14 . the pressure generating assembly 12 comprises a main body 16 , an actuating body 18 , a piston 20 and its sealing member 22 such as an oring , a central stud 24 such as a bolt , and a shield 26 in front of a plurality of venting openings 28 in the wall of the main body 16 with a gap 30 preferably of about 1 - 2 mm . the chamber 14 comprises of a chamber cavity 32 and a chamber opening 34 located at the bottom and top parts of the chamber 14 respectively . the chamber cavity 32 receiving materials to be exposed to hydrostatic pressure including a sample , a fluid , and air , having a higher maximum pressure with a higher fluid to air volume ratio . preferably , the sample placed in the chamber cavity 32 can be a biological tissue or a cell culture dish and the liquid can be a cell culture media . the chamber opening 34 has a threaded wall and is where the main body 16 of the pressure generating assembly 12 is mounted and sealed to the chamber 14 using a sealing member 36 , such as an oring , that sits in a half grove on a step 38 above the chamber cavity 32 . a step 40 above the step 38 makes the sealing surface for a face seal between the main body 16 of the pressure generating assembly 12 and the chamber 14 . main body 16 comprises a cylindrical passageway defining a cylinder 42 at its lower part and a cavity 44 ( main body cavity ) with an opening on top . the cylinder 42 extends between the main body cavity 44 and the exterior of the main body 16 . the main body 16 is threaded internally on the wall 46 of the main body cavity 44 as well as externally on its outer surface 48 . the pressure generating assembly 12 can be threadebly mounted and sealed to the chamber 14 by turning the main body 16 into the chamber opening 34 . there is preferably a smooth surface 50 with a reduced section at the lower end of the main body 16 that allows the full travel of the main body 16 into the chamber opening 34 until it pushes against the step 40 and the sealing member 36 making a sealed connection . at its upper end , the piston 20 has a flange 52 , with a head 54 , preferably rounded , and a step 56 . the flange 52 is loosely secured in the actuating body 18 for actuation thereof , and the lower end 58 of the piston 20 moves in the cylinder 42 of the main body 16 to generate pressure . through the actuating body 18 there is an internal passageway 60 which is threaded on its upper part 62 and having a step 64 at its lower end above which the piston flange 52 is fitted for actuation thereof . the actuating body 18 is threaded on its outer surface 66 and moves threadably inside the cavity 44 of the main body 16 . the actuating body 18 provides an actuating means for holding and moving the piston 20 . the piston 20 can move down and up in the cylinder 42 of the main body 16 by screwing and unscrewing rotation of the actuating body 18 in and out of the main body 16 , which pushes and pulls the piston 20 in the cylinder 42 . there is a taper 68 at the top of the cylinder 42 to provide a smooth entry of the piston 20 into the cylinder 42 . the central stud 24 can be screwed in the threaded portion 62 of the internal passageway 60 of the actuating body 18 . the lower wall 70 of the central stud 24 can touch the head 54 of the flange 52 of the piston 20 by screwing the actuating body 18 into the main body 16 pushing the piston 20 into the cylinder 42 of the main body 16 generating pressure in the chamber cavity 32 . self adjusting means for entering the piston 20 inside the cylinder 42 is provided by having the flange 52 , with the rounded head 54 , loosely secured above the step 64 in the actuating body 18 , and having the taper 68 at the top of the cylinder 42 , which allows a smooth entry of the piston 20 into the cylinder 42 , prevents jamming of the piston 20 inside the cylinder 42 , and improves sealing performance of the sealing member 22 between the piston 20 and the cylinder 42 . the amount of pressure generated in the chamber cavity 32 can be monitored by using a pressure monitoring device 72 , preferably an autoclavable or a sanitary pressure gauge . the term pressure gauge represents any pressure monitoring device such as a mechanical pressure gauge as well as different types of pressure transducers , pressure sensors , and pressure transmitters . the pressure gauge 72 is connected to the chamber 14 via a passageway including two sections of an outer hole 74 and an inner hole 76 . the outer hole 74 is threaded receiving the pressure gauge 72 , and the inner hole 76 connects the outer hole 74 to the chamber cavity 32 . there are two steps 78 and 80 between the outer hole 74 and inner hole 76 providing a sealing surface and a half groove gland respectively for a sealing member 82 such as an oring . the pressure gauge 72 can be threadably mounted in the outer hole 74 . there is preferably a clearance groove or undercut 84 at the end of threaded portion of the outer hole 74 before the step 78 allowing the full travel of the stud 86 of the pressure gauge 72 to the end of the outer hole 74 pushing against the step 78 and sealing member 82 making a face seal between the pressure gauge 72 and the chamber 14 . as shown in fig2 , by unscrewing the actuating body 18 out of the main body 16 , the wall of the step 64 of actuating body 18 can touch the wall of the step 56 of the piston 20 , pulling the piston 20 out of the cylinder 42 of the main body 16 relieving pressure in the chamber cavity 32 . the actuating body 18 can be unscrewed and moved upward in the main body 16 until it uncovers the venting openings 28 from inside of the main body 16 in the cavity 44 . with the venting openings 28 uncovered and the piston 20 out of the cylinder 42 , the vital gases required for survival of cells or biological tissues placed in the chamber cavity 32 can then be provided when the assembly is placed in an incubator . to reduce the chance of contamination , the shield 26 is placed in front of the venting openings 28 with a gap 30 preferably of about 1 - 2 mm . the shield 26 can be threaded on its inner surface 88 and installed threadably on the main body 16 in front of the venting openings 28 . in an alternative method , instead of the shield 26 , filters may be installed in the venting openings 28 . in operation , referring to fig1 , a sample to be treated with the hydrostatic pressure is placed in the chamber cavity 32 , then the main body 16 is mounted and sealed in the chamber opening 34 . then , from the top opening of the cylinder 42 in the main body 16 , the chamber cavity 32 and the cylinder 42 can be filled with a fluid , such as a cell culture media . finally , the actuating body 18 is mounted in the cavity 44 of the main body 16 and hydrostatic pressure is generated in the chamber cavity 32 by rotating and screwing the actuating body 18 in the main body 16 as described . the chamber cavity 32 and the cylinder 42 can be filled with fluid and air , generating higher pressure with more fluid volume and having the maximum pressure when the chamber cavity 32 and the cylinder 42 are fully filled with liquid . depending on the size of the piston 20 , hydrostatic pressure magnitude , and static or dynamic choice of hydrostatic pressure , rotating action for screwing and unscrewing of the actuating body 18 into and out of the main body 16 can be done by hand without any tool , by hand with a tool such as a wrench , or by using a coupling mechanism to a rotary actuator . for turning and holding purposes , handles may be installed on the actuating body 18 , the main body 16 , and the chamber 14 . a prototype of the first embodiment shown in fig1 and 2 was made and tested successfully in all of its operating procedure as described . using the prototype with a piston of 8 mm , pressures up to 10 mpa could easily be generated by rotating the actuating body 18 simply by hand and without any tools . in a hydrostatic pressure generator device , such as the hydrostatic pressure generator device 10 , other sealing systems for sealing of the pressure gauge 72 and the main body 16 to the chamber 14 may be used . for example , a gasket or an oring with different gland types can be used to seal the main body 16 or the pressure gauge 72 to the chamber 14 , or a teflon tape can be used to seal the pressure gauge 72 to the chamber 14 . however , the sealing system shown in fig1 and 2 is preferable . preferably , the chamber 14 , the chamber cavity 32 , the chamber opening 34 , the actuating body 18 , and the main body 16 have cylindrical shapes as shown in fig1 and 2 . the size of the hydrostatic pressure generator device can vary according to the size of its chamber cavity 32 which may be a miniature chamber to hold a small piece of a tissue , a small chamber to hold one culture dish , or a large chamber to hold a cell culture plate . the preferable sizes for the chamber cavity 32 are those which can receive a small commercially available single culture dish such as a 35 mm diameter cell culture dish or single cell culture dish inserts of diameters equal or less than 30 mm , plus 2 - 5 mm extra space around and on top of a dish for handling . the dishes can also be placed in the chamber cavity 32 in a stack and the height of the chamber cavity 32 can be adjusted according to the number of dishes in the stack . the construction details of the invention , such as the hydrostatic pressure generator device 10 shown in fig1 and 2 , are that the hydrostatic pressure generator device 10 preferably is made from materials which are autoclavable , resistant to corrosion , and do not cause any destructive reaction with the cell culture media . the preferable materials are polycarbonate , polyamide , teflon , and stainless steel . the materials should also be sufficiently rigid and strong to hold a hydrostatic pressure of interest according to the size of the hydrostatic pressure generator device 10 . stainless steel is preferable for miniature sizes which strength is of prime importance . polyamide and teflon may be used for large sizes when having a low weight becomes important . more preferably polycarbonate and still more preferably a combination of polycarbonate and stainless steel may be used for having an optimum strength and size with a low weight . reference will now be made to fig3 which shows another embodiment of the present invention , generally denoted by the reference 90 , comprising a pressure generating assembly 92 and a chamber 94 . in fig3 , for simplicity and brevity , like components are given the same reference numeral as in the first embodiment shown in fig1 and 2 , and the description is not repeated . in the embodiment of fig3 , the chamber 94 and a main body 96 respectively replace the chamber 14 and main body 16 of the first embodiment shown in fig1 and 2 . in the embodiment of fig3 , the main body 96 includes a threaded passageway 98 ( main body passageway ) without any cylinder at its lower part , and the piston 20 moves directly in the chamber cavity 32 to generate pressure . there is a taper 100 at the top of the chamber cavity 32 to provide a smooth entry of the piston 20 into the chamber cavity 32 . the pressure generating assembly 92 can be mounted to the chamber 94 by screwing the main body 96 into the chamber opening 34 without using any sealing . in this embodiment , the main body 96 can be a separate part and to be connected to the chamber 94 as described and shown in fig3 , or the main body 96 can be integral with the chamber 14 wherein the main body 96 is an extension of the chamber opening 34 . for generating pressures up to 10 mpa by hand without any tools , this embodiment is preferable for a small hydrostatic pressure generator device with a cylindrical chamber cavity 32 of a diameter of less than 10 mm and more preferably less than 8 mm . reference will now be made to fig4 which shows another embodiment of the present invention , when a hydrostatic pressure generator device , generally denoted by the reference 102 , is mainly operated by an external actuator . the hydrostatic pressure generator device 102 comprises a pressure generating assembly 104 and the chamber 14 . in fig4 , for simplicity and brevity , like components are given the same reference numeral as in the first embodiment shown in fig1 and 2 , and the description is not repeated . in the embodiment of fig4 , a main body 106 , an actuating body 108 , and a piston 110 respectively replace the main body 16 , the actuating body 18 , and the piston 20 of the first embodiment shown in fig1 and 2 . in more detail , still referring to the invention of fig4 , the actuating body 108 comprises a central passageway 112 with a smooth surface throughout its length wherein the piston 110 passes through and outside the actuating body 108 . the piston 110 comprises a head 114 which can be engaged with an external actuator . there is a flange 116 on the piston 110 with an upper surface 118 which is located under the lower surface 120 of the actuating body 108 . by screwing the actuating body 108 into the main body 106 , the lower surface 120 of actuating body 108 touches the upper surface 118 of the piston flange 116 pushing the piston 110 in the cylinder 42 of the main body 106 generating a hydrostatic pressure as a baseline static hydrostatic pressure preload . from the baseline pressure , using an external actuator , applying a static or dynamic load at the piston head 114 can then generate a static or dynamic hydrostatic pressure . in further detail , still referring to the invention of fig4 , there is a passageway , which maybe in a form of a vertical hole 122 connected to a horizontal hole 124 , connecting the cavity 44 of the main body 106 to the inside of the cylinder 42 at its upper end allowing passage of air or incubator gas for breathing during dynamic movement of the piston 110 . this embodiment can also work independent of an external actuator for generating hydrostatic pressure as described for generating a static hydrostatic pressure preload . unloading of the hydrostatic pressure can be done by means pulling the piston 110 out of the cylinder 42 such as by unscrewing the actuating body 108 out of the main body 106 until it pushes against a pin 126 which can be fit in a hole 128 at the top of the piston 110 and pulling the piston 110 out of the cylinder 42 of the main body 106 . reference will now be made to fig5 which shows another embodiment of the present invention , when a hydrostatic pressure generator device generally denoted by the reference 130 , is used for generating negative pressure , lower than atmospheric pressure , by suction . the hydrostatic pressure generator device 130 comprises a pressure generating assembly 132 and a chamber 134 . in fig5 , for simplicity and brevity , like components are given the same reference numeral as in the first embodiment shown in fig1 and 2 , and the description is not repeated . in the embodiment of fig5 , a main body 136 and the chamber 134 respectively replace the main body 16 and the chamber 14 of the first embodiment shown in fig1 and 2 , and a nut 138 with its sealing assembly is added . in more detail , still referring to the invention of fig5 , the sealing systems of the main body 136 and the pressure gauge 72 to the chamber 134 are preferably face seals with groove glands suitable for a negative pressure in the chamber cavity 32 . the sealing of the main body 136 to the chamber 134 includes the sealing member 36 , such as an oring , fitted in a groove 140 in the step 142 at the top of the chamber cavity 32 . the sealing of the pressure gauge 72 to the chamber 134 includes the sealing member 82 , such as an oring , fitted in the groove 144 in a step 146 between the outer hole 76 and the inner hole 74 . in the main body 136 , there is a bleeding passageway which may consist of a vertical section 148 and a horizontal section 150 connecting the chamber cavity 32 to the outside of the chamber 134 through the lower part of main body 136 . the horizontal section 150 can be sealed with a face seal assembly consisting of the nut 138 and a sealing member 152 such as an oring , sitting in a groove 154 . in the embodiment of fig5 , the negative pressure in the chamber cavity 32 can be generated by removing the nut 138 from the horizontal section 150 , then screwing the actuating body 18 into the main body 136 pushing the piston 20 into the cylinder 42 of the main body 136 until the fluid in the chamber rises up to the horizontal section 150 , then screwing back the nut 138 in the horizontal section 150 and seal the passage , and finally generating negative pressure by unscrewing the actuating body 18 out of the main body 136 and pulling the piston 20 out of the cylinder 42 . reference will now be made to fig6 which shows another embodiment of the present invention generally denoted by the reference 156 comprising a pressure generating assembly 158 and a chamber 160 . in fig6 , for simplicity and brevity , like components are given the same reference numeral as in the first embodiment shown in fig1 and 2 , and the description is not repeated . in the embodiment of fig6 , the chamber 160 , a main body 162 , an actuating body 164 , and a central stud 166 respectively replace the chamber 14 , main body 16 , the actuating body 18 , and the central stud 24 of the first embodiment shown in fig1 and 2 . in fig6 an alternative connecting means to that of the first embodiment shown in fig1 and 2 , for connecting the main body 162 to the chamber 160 is shown , which uses a plurality of screws 168 to attach the main body 162 to the chamber 160 . the main body 162 comprises a lower part 170 with a smooth surface which fits in the chamber opening 172 which also have a smooth surface . there is a flange 174 on the main body 162 with a plurality of openings 176 where the screws 168 can pass . on the top edge surface of the chamber 160 , there are plurality of threaded holes 178 matching the treads of screws 168 . the screws 168 can pass through the openings 176 of the flange 174 and be screwed in the threaded holes 178 in the chamber 160 connecting the main body 162 into chamber 160 pushing the lower surface of the main body 162 against the step 40 and the sealing member 36 sealing the connection . still referring to fig6 , in case of using a material such as teflon which may not be strong enough for the threaded holes 178 to hold the screws 168 , the holes 178 in the chamber 160 may be extended as a passageway to the of the chamber 160 where the screws 168 with a long stem can pass and be fixed with a bolt at the bottom from outside of the chamber 160 . the main body 162 is preferably used with the chamber cavity 32 of a diameter preferably larger than 40 mm . the main body 164 can also be used with the actuating body 18 and the central stud 24 of the first embodiment shown in fig1 and 2 . in the embodiment of fig6 , the central stud 166 has the same function as the central stud 24 of the first embodiment , shown in fig1 and 2 , in restraining the flange 52 of the piston 20 . the central stud 166 comprises a smooth surface 180 and a hole 182 across its upper end . the actuating body 164 also comprises a smooth passageway 184 with a hole 186 at its upper end . the central stud 166 can fit in the passageway 184 and fixed with a pin 188 which passes through the holes 182 and 186 . the pin 188 can also be used as a handle for rotating the actuating body 164 pushing the piston 20 in the cylinder 42 of the main body 162 generating pressure . referring to fig6 , the actuating body 164 operated with the pin 188 as a handle is preferably used with the piston 20 of a diameter of less than 8 mm so that it could be rotated by hand to generate a hydrostatic pressure of at least up to 10 mpa . the actuating body 164 with the stud 166 , shown in fig6 , can also be used with the main body 16 and the chamber 14 of the first embodiment , shown in fig1 and 2 . in the embodiment of fig6 , the cross sectional area of the chamber cavity 32 can have any shape which preferably matches the shape of the main body 162 cross sectional area . for example , both the chamber cavity 32 and the main body 162 preferably have the same shape of either circular or rectangular sections , but a circular section with a cylindrical chamber is preferable . in the described embodiments , a hydrostatic pressure generator device , such as the hydrostatic pressure generator device 10 shown in fig1 and 2 may also be used without any pressure gauge 72 and instead the pressure can be calculated by measuring the applied torque on the actuating body 18 using a formula relating the applied torque to the pressure . similarly , a hydrostatic pressure generator device , such as the hydrostatic pressure generator device 102 shown in fig4 , may also be used without any pressure gauge 72 and instead the pressure can be calculated by measuring the axial load on the piston 110 using a formula relating the axial load to the pressure . while the foregoing written description of the invention enables one of ordinary skill to make and use what is considered presently to be the best mode thereof , those of ordinary skill will understand and appreciate the existence of variations , combinations , and equivalents of the specific embodiment , method , and examples herein . the invention should therefore not be limited by the above described embodiment , method , and examples , but by all embodiments and methods within the scope and spirit of the invention as claimed . kasra et al ., abstract of a publication entitled “ effect of dynamic hydrostatic loading on rabbit disc cells ”, american society of mechanical engineers , bioengineering division ( publication ) bed , 50 : 191 - 192 , 2001 . kasra et al ., “ effect of dynamic hydrostatic pressure on intervertebral disc cells : a rabbit model ” journal of orthopaedic research , 21 : 597 - 603 , 2003 . kasra et al ., “ frequency response of pig intervertebral disc cells subjected to dynamic hydrostatic pressure ”, journal of orthopaedic research ., 24 ( 10 ): 1967 - 1973 , 2006 . smith et al ., “ time - dependent effects of intermittent hydrostatic pressure on articular chondrocyte type ii collagen and 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