<PAGE>

                                                                   EXHIBIT 10.19

         THESE SECURITIES HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF
         1933 ("THE ACT") OR UNDER THE SECURITIES OR BLUE SKY LAWS OF ANY STATE
         (THE "LAWS"). THESE SECURITIES MAY NOT BE SOLD, OFFERED FOR SALE,
         PLEDGED OR HYPOTHECATED IN THE ABSENCE OF A REGISTRATION AND
         QUALIFICATION OF THESE SECURITIES UNDER THE ACT AND THE LAWS OR AN
         OPINION OF COUNSEL SATISFACTORY TO THE ISSUER THAT SUCH REGISTRATION
         AND QUALIFICATION ARE NOT REQUIRED UNDER THE ACT AND THE LAWS.


                                WARRANT AGREEMENT

         THIS WARRANT AGREEMENT (this "AGREEMENT") is entered into and effective
as of April 11, 2003 (the "EFFECTIVE DATE"), by and between MicroIslet, Inc., a
Nevada corporation (the "COMPANY"), and John J. Hagenbuch, Trustee U/D/T dated
September 13, 1995 ("WARRANTHOLDER").

         NOW, THEREFORE, in consideration of the mutual covenants and agreements
contained in this Agreement, the Company and the Warrantholder certify and agree
as follows:

         1. GRANT OF THE RIGHT TO PURCHASE COMMON STOCK. For value received, the
adequacy of which is hereby acknowledged, the Company hereby grants to
Warrantholder, and Warrantholder is entitled to, upon the terms and subject to
the conditions set forth in this Agreement, a warrant (the "WARRANT") to
subscribe for and purchase from the Company a number of shares of the Company's
Common Stock (the "SHARES") equal to FIFTY THOUSAND (50,000) Shares of the
Company's Common Stock at a purchase price of ONE Dollar and FORTY-NINE Cents
($1.49) per Share (the "EXERCISE PRICE"). This Warrant is being issued pursuant
to the 120 Day Note between the Holder and the Company of even date herewith
(the "NOTE"). Notwithstanding anything to the contrary in this Agreement, the
rights under this Warrant are subject to the limitations stated in the Note.

         2. EXPIRATION. The Warrant shall expire and cease to be exercisable at
5:00 p.m. Pacific time on the tenth anniversary of the Effective Date.

         3. METHOD OF EXERCISE; PAYMENT; ISSUANCE OF SHARES. Subject to Section
2 hereof, the purchase right represented by the Warrant may be exercised by the
Warrantholder, in whole or in part, by tendering to the Company a duly executed
Notice of Exercise in the form attached as EXHIBIT A at the principal office of
the Company and by payment to the Company, by check, of an amount equal to the
then applicable Exercise Price multiplied by the number of shares then being
purchased. In the event of any exercise of the rights represented by this
Agreement, certificates for the shares of stock so purchased shall be in the
name of, and delivered to, Warrantholder, or as Warrantholder may direct
(subject to the terms of transfer contained herein). Such delivery shall be made
within thirty (30) days after exercise and at the Company's expense. The shares
so issued upon exercise of the rights represented by this Agreement shall be
duly authorized, validly issued, fully paid and non-assessable.


<PAGE>

         4. RESERVATION OF SHARES. The Company shall at all times have
authorized and reserved a sufficient number of shares of its Common Stock to
provide for the exercise of the rights to purchase the Shares as provided in
this Agreement.

         5. NO RIGHTS AS STOCKHOLDER. This Agreement does not entitle
Warrantholder to any voting rights or other rights as a stockholder of the
Company prior to the purchase of the Shares as provided in this Agreement.

         6. ADJUSTMENT RIGHTS. The Exercise Price and the number of Shares
purchasable hereunder are subject to adjustment from time to time as follows:

                  6.1 MERGER AND SALE OF ASSETS. If at any time there shall be
(i) a reorganization of the shares of the Company's Common Stock (other than a
combination, reclassification, exchange or subdivision of shares otherwise
provided for herein), or a merger or consolidation of the Company with or into
another corporation where the Company is not the surviving corporation, or a
reverse triangular merger in which the Company is the surviving entity but the
shares of the Company's capital stock outstanding immediately prior to the
merger are converted by virtue of the merger into other property, whether in the
form of securities, cash, or otherwise, or (iii) the sale of all or
substantially all of the Company's properties and assets to any other person,
then, as a part of such reorganization, merger, consolidation or sale, whether
for stock, cash, or other consideration, lawful provision shall be made so that
Warrantholder shall thereafter be entitled to receive upon exercise of its
Warrants the number of shares of Common Stock or other securities of the
successor corporation resulting from such merger or consolidation to which
Warrantholder would have been entitled if the Warrants had been exercised
immediately prior to such capital reorganization, merger, consolidation or sale.
In any such case, appropriate adjustment (as determined in good faith by the
Company's Board of Directors) shall be made in the application of the provisions
of this Warrant Agreement with respect to the rights and interest of
Warrantholder after such reorganization, merger, consolidation or sale so that
the provisions of this Warrant Agreement (including adjustments of the Exercise
Price and the number of Shares issuable pursuant to the terms and conditions of
this Warrant Agreement) shall be applicable after such event, as near as
reasonably may be, in relation to any shares deliverable after that event upon
the exercise of the Warrants.

                  6.2 RECLASSIFICATION OF SHARES. If the Company at any time
shall, by combination, reclassification, exchange or subdivision of securities
or otherwise, change all of the outstanding shares of Common Stock into the same
or a different number of securities of any other class or classes, this Warrant
Agreement shall thereafter represent the right to acquire such number and kind
of securities as would have been issuable hereunder had the Warrantholder
exercised its rights with respect to all of the shares then represented by this
Warrant Agreement immediately prior to such combination, reclassification,
exchange, subdivision or other change.

                  6.3 SUBDIVISION OR COMBINATION OF SHARES. If the Company at
any time shall combine or subdivide its Common Stock, the Exercise Price shall
be proportionately decreased in the case of a subdivision, or proportionately
increased in the case of a combination.

                                       2
<PAGE>

                  6.4 STOCK DIVIDENDS. If the Company at any time shall pay a
dividend payable in the Company's Common Stock, then the Exercise Price shall be
adjusted, from and after the date of determination of shareholders entitled to
receive such dividend, to a price determined by multiplying the Exercise Price
in effect immediately prior to such date of determination by a fraction (i) the
numerator of which shall be the total number of all shares of the Company's
Common Stock outstanding immediately prior to such dividend (assuming all
convertible securities are then converted into Common Stock) and (ii) the
denominator of which shall be the total number of all shares of the Company's
Common Stock outstanding immediately after such dividend (assuming all
convertible securities are then converted into Common Stock). Warrantholder
shall thereafter be entitled to purchase, at the Exercise Price resulting from
such adjustment, the number of shares of Common Stock (calculated to the nearest
whole share) obtained by multiplying the Exercise Price in effect immediately
prior to such adjustment by the number of shares of Common Stock issuable upon
the exercise hereof immediately prior to such adjustment and dividing the
product thereof by the Exercise Price resulting from such adjustment.

         7. WARRANT NONTRANSFERABLE. The Warrant may not be sold, pledged,
assigned or transferred in any manner without the written consent of the
Company.

         8. SECURITIES ISSUES. Warrantholder, intending that the Company rely
upon the following representations and covenants of Warrantholder, which by
execution of this Agreement, Warrantholder hereby confirms:

                  8.1 ACCREDITED INVESTOR. Warrantholder is familiar with the
definition of "accredited investor" set forth in Rule 501 of Regulation D
promulgated under the Securities Act of 1933, as amended. Warrantholder is an
accredited investor as so defined.

                  8.2 ACQUISITION FOR OWN ACCOUNT. Warrantholder is entering
into this Agreement for Warrantholder's own account and not with a view to or
for sale in connection with any distribution of securities.

                  8.3 NO TRANSFERS CONTEMPLATED. Warrantholder does not
presently have any contracts, undertaking, agreement or arrangement with any
person to sell, transfer or grant participation to such person or to any third
person, with respect to any securities of the Company.

                  8.4 TRUE INVESTMENT PURPOSE. Warrantholder has not been
organized for the purpose of entering into this Agreement.

                  8.5 RESTRICTIONS ON ACQUIRED SECURITIES. Warrantholder
acknowledges that any securities acquired pursuant to this Agreement may not be
sold, pledged, assigned or transferred in any manner, except pursuant to
registration and qualification under applicable securities laws, or if an
exemption from such registration or qualification is applicable.

                  8.6 INVESTMENT EXPERIENCE. Warrantholder is an investor in
securities of small capitalization public companies and is able to fend for
itself, bear the economic risk of its investment and evaluate the merits and
risks of the transactions provided in this Agreement.

                                       3
<PAGE>

                  8.7 ACCESS TO INFORMATION. Warrantholder has had access to,
and has reviewed as it sees fit, all of the Company's public reports filed with
the Securities and Exchange Commission. Warrantholder acknowledges that it has
not received any material information in connection with this investment which
is not contained in, or which is contrary to, the information in such public
reports, and Warrantholder has relied only on such public reports in connection
with its investment decision.

                  8.8 RESTRICTED SHARES/LEGEND. Warrantholder understands that
the Shares issuable upon the exercise of the Warrant under this Agreement shall
be "restricted securities" as that term is defined in Rule 144 promulgated under
the Securities Act of 1933, as amended, and shall bear a legend in the form
substantially as follows:

         THESE SECURITIES HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF
         1933 (THE "ACT") OR UNDER THE SECURITIES OR BLUE SKY LAWS OF ANY STATE
         (THE "LAWS"). THESE SECURITIES MAY NOT BE SOLD, OFFERED FOR SALE,
         PLEDGED OR HYPOTHECATED IN THE ABSENCE OF A REGISTRATION AND
         QUALIFICATION OF THESE SECURITIES UNDER THE ACT AND THE LAWS OR AN
         OPINION OF COUNSEL SATISFACTORY TO THE ISSUER THAT SUCH REGISTRATION
         AND QUALIFICATION ARE NOT REQUIRED UNDER THE ACT AND THE LAWS.

                  8.9 NO GENERAL SOLICITATION. Warrantholder has not seen or
received any advertisement or general solicitation in connection with this
Agreement or the Warrant.

         9. MARKET STAND-OFF. If Warrantholder's Shares are not registered, then
in connection with any underwritten public offering by the Company of its equity
securities pursuant to an effective registration statement filed under the
Securities Act of 1933, as amended, including the Company's initial public
offering, Warrantholder shall not sell, make any short sale of, loan,
hypothecate, pledge, grant any option for the purchase of, or otherwise dispose
of or transfer for value or otherwise agree to engage in any of the foregoing
transactions with respect to any of the Shares without the prior written consent
of the Company and its underwriters, for such period of time from and after the
effective date of such registration statement as may be requested by the Company
or such underwriters, up to a maximum of one hundred eighty (180) days, so long
as such stand-off provisions are no more onerous than those applicable to any
securities held by any officer or director of the Company.

         10. MISCELLANEOUS.

                  10.1 GOVERNING LAW. This Agreement is entered into in San
Diego, California, shall be performed in California, and shall be interpreted,
enforced and adjudicated in Carlsbad, California under the internal laws of the
State of California without regard to California's conflict-of-law provisions.

                  10.2 ENTIRE AGREEMENT. This Agreement and the Note constitutes
the final, complete and exclusive agreement between the parties pertaining to
the subject of this Agreement, and supersedes all prior and contemporaneous
agreements. This Agreement represents the warrant required to be delivered
pursuant to the Note. None of the provisions of this Agreement shall be deemed,
or shall constitute, a waiver of any other provision, whether or not similar,
nor shall any waiver constitute a continuing waiver. No waiver shall be binding
unless executed in writing by the party making the waiver. Any changes or
supplements to this Agreement must be in writing and signed by both of the
parties.

                                       4
<PAGE>

                  10.3 ASSIGNMENT. Not in derogation of Section 7 hereof, this
Agreement shall be binding on, and shall inure to the benefit of, the parties
and their respective heirs, legal representatives, successors and assigns.

                  10.4 NOTICES, ETC. All notices, requests, demands or other
communications that are required or permitted under this Agreement shall be in
writing and shall be deemed to have been given at the earlier of the date when
actually delivered to a party or three (3) days after being deposited in the
United States mail, postage prepaid, return receipt requested, and addressed as
follows, unless and until any of such parties notifies the others in accordance
with this Section of a change of address:

                 The "Company":    MicroIslet, Inc.
                                   6370 Nancy Ridge Drive, Suite 112
                                   San Diego, CA 92121
                                   Attn: Chief Financial Officer

                 "Warrantholder":  John J. Hagenbuch, Trustee U/D/T dated
                                   September 13, 1995
                                   _____________________________________________

                                   _____________________________________________

                  10.5 SEVERABILITY. In the event that any one or more of the
provisions contained in this Agreement or in any other document referenced in
this Agreement, shall, for any reason, be held to be invalid, illegal or
unenforceable in any respect, such invalidity, illegality or unenforceability
shall not affect any other provision of this Agreement or any other such
document.

                  10.6 TIME IS OF THE ESSENCE. Time is absolutely of the essence
in construing each provision of this Agreement.

                  10.7 INTERPRETATION. The headings set forth in this Agreement
are for convenience only and shall not be used in interpreting this Agreement.

                  10.8 COUNTERPARTS. This Agreement may be executed in one or
more counterparts, each of which shall be deemed an original, but all of which
taken together shall constitute one and the same instrument. A faxed signature
shall be as valid as an originally executed signature.

                [REMAINDER OF THIS PAGE INTENTIONALLY LEFT BLANK]


                                       5
<PAGE>



         IN WITNESS WHEREOF, the parties have caused this Agreement to be
executed as of the Effective Date.

                                  "Company"

                                  MICROISLET, INC.,
                                  a Nevada corporation


                                  By:
                                       -----------------------------------------
                                       John F. Steel IV, Chief Executive Officer

                                  "Warrantholder"

                                  JOHN J. HAGENBUCH, TRUSTEE U/D/T
                                  DATED SEPTEMBER 13, 1995


                                  By:
                                       -----------------------------------------
                                       John J. Hagenbuch, Trustee



                                       6
<PAGE>

                                    EXHIBIT A

                               NOTICE OF EXERCISE
                               ------------------


To:      Chief Financial Officer
         MicroIslet, Inc.


1.       The undersigned Warrantholder ("Warrantholder") elects to acquire
         shares of the Common Stock of MicroIslet, Inc., a Nevada corporation
         (the "Company"), pursuant to the terms of the Warrant Agreement dated
         as of April 11, 2003 (the "Warrant").

2.       The Warrantholder elects to purchase _____________ shares of Common
         Stock as provided in Section 3 and tenders herewith a check in the
         amount of $___________ as payment of the purchase price.

3.       In exercising its rights to purchase the Common Stock of the Company,
         the undersigned hereby confirms and acknowledges the representations
         made in Section 8 of the Warrant.

         4. Please issue a certificate representing the shares of the Common
         Stock in the name of the undersigned or in such other name as is
         specified below:

         Name:
                      ---------------------------------------------------------
         Address:
                      ---------------------------------------------------------

                      ---------------------------------------------------------
         Taxpayer I.D No.:
                            ----------------------------------

                                    WARRANTHOLDER


                                    By:
                                        ----------------------------------------
                                         Name:
                                               ---------------------------------
                                         Title:
                                                 -------------------------------

                                    Date:
                                             -----------------------------------