Exhibit 10.3


May 8, 2006


Teragenix Corporation


5440 NW 33rd Avenue, Suite 108


Ft. Lauderdale, FL 33309


HemaCare Corporation


21101 Oxnard Street


Woodland Hills, California 91367


Re:  Agreement to Replace Promissory Note


Dear Joe and Judi:


Reference is made to the following:


1.Promissory Note in the principal amount of $450,000, dated
November 11, 2005, issued by Teragenix Corporation (“Teragenix”) to the order of Lawrence Feldman (the “Existing
Note”); and


2.Non-Binding Letter of Intent dated March 10, 2006 between HemaCare
Corporation (“HemaCare”) and Teragenix (the “LOI”).


The LOI sets forth the proposed terms for the acquisition of 100%
of the outstanding capital stock of Teragenix by HemaCare (the “Acquisition”).  One of the terms of the
Acquisition is the replacement of the Existing Note with a new subordinated promissory note in the principal amount of $250,000,
the form of which is attached hereto as Exhibit “A” (the “New Note”).  In furtherance
of their desire to proceed with the Acquisition, Teragenix and HemaCare have requested that the undersigned agree to replace the
Existing Note with the New Note.  The replacement of the Existing Note with the New Note would occur concurrently with the
closing of the Acquisition.


In consideration of the shorter time to maturity in the New Note
relative to the Existing Note and the obligation of Teragenix to pay interest annually in the New Note, as well as the benefits
which the undersigned expects Teragenix to realize as a result of the consummation of the Acquisition, the undersigned hereby agrees
to accept, concurrently with the closing of the Acquisition, the New Note in substitution for the Existing Note and agrees to the
terms of the New Note as reflected on Exhibit “A”.



     

     

    

 


Letter to Teragenix and HemaCare


May 8, 2006


This letter agreement constitutes the entire agreement among the
undersigned, Teragenix and HemaCare with respect to the subject matter hereof and may be amended or modified only in a written
agreement among such parties.  This letter agreement may be executed in any number of counterparts and by different parties
on separate counterparts.  Each of such counterparts shall be deemed to be an original, and all of such counterparts, taken
together, shall constitute but one and the same agreement.  Delivery of an executed counterpart of this letter by telefacsimile
shall be equally effective as delivery of a manually executed counterpart.


[signature page to follow]


 



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Letter to Teragenix and HemaCare


May 8, 2006


 


Sincerely,


 


	/s/ Lawrence Feldman	 
	Lawrence Feldman


 


Acknowledged and Agreed:


TERAGENIX CORPORATION


 


	By:	  /s/ Joseph Mauro	 


Title:  President


 


HEMACARE CORPORATION


 


	By:	  /s/ Judi Irving	 


Title:  President & CEO



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EXHIBIT “A”


Form of New Note


 


AMENDED AND RESTATED SUBORDINATED PROMISSORY
NOTE


	$250,000.00	 	Fort Lauderdale, Florida
	 	 	August 29, 2006


 


FOR VALUE RECEIVED, TERAGENIX
CORPORATION, a Florida corporation (the “Payor”), promises to pay to the order of LAWRENCE FELDMAN (the
“Payee”) at 777 17th Street, Miami Beach, FL 33139-1854, the principal sum of TWO HUNDRED FIFTY THOUSAND DOLLARS
($250,000), together with interest from the date hereof at a rate equal to 7% simple interest per annum.


1.            
Payments of Principal and Interest; Time of the Essence.  Principal under this note shall be due and payable in four
(4) equal, consecutive, annual installments in the amount of SIXTY TWO THOUSAND FIVE HUNDRED DOLLARS ($62,500) on each anniversary
of the date of this note commencing on the first anniversary and continuing through the fourth anniversary, at which time all principal
that remains unpaid shall be due and payable in full.  Accrued but unpaid interest to the date of each principal payment shall
be due and payable on such date and any remaining accrued but unpaid interest shall be due and payable concurrently with the final
principal payment under this note.  Time is of the essence.


2.            
Prepayment.  Subject to the terms of Section 5 below, this note may be prepaid in whole or in part at any time without
premium or penalty.


3.             
Acceleration after Default; Default Interest Rate.  If any payment remains unpaid after the same shall become due,
the entire principal sum shall forthwith become due at the option of the holder of this note.  While this note is in default,
it shall bear interest at the maximum rate of 10% per annum.


4.            
Florida Documentary Stamp Tax. Florida documentary stamp tax required by law in the amount of $2,450 has been paid directly
to the Florida Department of Revenue.


5.            
Subordination to Senior Debt.  The Payee, by acceptance of this note, agrees that the payment of the principal and
interest of this note is subordinated to the extent and as provided below and undertakes, as a condition to the right to receive
any payments hereunder, to execute such subordination agreements as may be requested by the Senior Lenders (as defined below) from
time to time.


(a)  As used herein, the term
“Senior Debt” shall mean any and all indebtedness of the Payor and all of its subsidiaries (collectively, the “Company”)
owed to Senior Lenders together with (i) all complete or partial refinancings of such indebtedness, (ii) any amendments,
restatements, extensions, modifications, amendments, renewals or substitutions with respect to the foregoing, (iii) interest,
reasonable attorney fees, other fees and other sums payable in respect thereof, and (iv) any interest accruing thereon after
the commencement of a bankruptcy proceeding, without regard to whether or not such interest is an allowed claim in such proceeding. 
The term “Senior Lenders” shall mean any institutional lender or lenders providing one or more senior secured credit
facilities to the Company.  Senior Debt shall be considered to be outstanding whenever any loan or loan commitment remains
outstanding under a loan agreement entered into with a Senior Lender.



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(b)  Except as specifically
permitted in Section 5(c) below, the Payee, by acceptance of this note, agrees that the Payee will not ask, demand, sue for, accept,
or receive payment from the Payor, by set-off or in any other manner, either in whole or in part, of any of the principal of or
interest accrued on the indebtedness evidenced by this note (the “Subordinated Indebtedness”).


(c)  The Payor shall
pay or cause to be paid to the Payee the Subordinated Indebtedness as set forth in Section 1 (and Section 3 with respect to interest
after default) above, except that the Payor shall not be required or permitted to make any payment on the Subordinated Indebtedness
if an event of default exists with respect to the Senior Debt until such time as such event of default has been cured or waived
by the Senior Lender.  The Payor may make prepayments of this note only upon receipt of written consent thereto from the Senior
Lender.


6.             
Miscellaneous.  Should it become necessary to collect this note through an attorney, the Payor hereby agrees to pay
all costs of collection, including a reasonable attorney’s fee.  Said reasonable attorney’s fee shall include
fees for services rendered in all appellate proceedings.  The Payor waives presentment for payment and protest for nonpayment
of this note; agrees to an extension of the time of payment of this note, without notice; and agrees that any such extensions will
not release the Payor’s liability hereon.


7.            
Choice of Law.  This note will be interpreted, construed and enforced in accordance with the laws of the State of Florida,
without giving effect to the application of the principles pertaining to conflicts of laws.


8.            
Amendment and Restatement of Note.  This note amends, restates, replaces and supercedes that that certain Promissory
Note (“Prior Note”) dated November 11, 2005, in the principal amount of $450,000, issued by the Payor to the order
of the Payee, which Prior Note upon Payor’s execution and delivery of this Note to Payee shall be null, void and of no further
legal force or effect.


 


9.            
WAIVER OF JURY TRIAL.  THE PAYOR HEREBY, AND THE PAYEE BY ACCEPTANCE OF THIS NOTE, KNOWINGLY, VOLUNTARILY
AND INTENTIONALLY WAIVE THE RIGHT EITHER MAY HAVE TO A TRIAL BY JURY IN RESPECT OF ANY LITIGATION BASED HEREON, OR ARISING OUT
OF, UNDER OR IN CONNECTION WITH THIS NOTE AND ANY AGREEMENT CONTEMPLATED TO BE EXECUTED IN CONJUNCTION HEREWITH OR ANY COURSE OF
CONDUCT, COURSE OR DEALING, STATEMENTS (WHETHER VERBAL OR WRITTEN) OR ACTIONS OF EITHER PARTY.  THIS PROVISION IS A MATERIAL
INDUCEMENT FOR THE PAYEE ACCEPTING THIS NOTE.


	 	TERAGENIX CORPORATION
	 	 	 
	 	 	 
	 	By:	/	 
	 	 	Joseph L Mauro, President


 



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