Weaver H. Gaines                                      Ixion Biotechnology, Inc.
Chairman and Chief Executive Officer               9 Progress Boulevard, Box 13
Tel: 386.462.3961                                             Alachua, FL 32615
Fax: 386.418.1583                                         www.ixion-biotech.com
Email: wgaines@ixion-biotech.com


                                         January 2, 2002

Mr. Jon Heimer
Valhallagatan 27
753 34 Uppsala
Sweden

                             Re: Offer of Employment

Dear Jon:

         This is to confirm our offer of employment as Vice  President,  Product
Development,  reporting to me as Chairman and CEO, or to the  President and COO.
Employment will commence on January 2, 2002, and terminate on or before December
31, 2002.  Employment may be extended  thereafter by mutual consent.  A position
description is attached.

         Ixion is a late preclinical stage biotechnology company specializing in
stem cell proliferation and differentiation and oxalate-related technology, with
headquarters and laboratories  located in the Progress Corporate Park,  Alachua,
Florida.

         This  offer  of  employment   is   conditioned   on  your   acceptance,
satisfactory references, approval by the board of Ixion, and a satisfactory test
result under subparagraph (e) below, and upon the following additional terms.

         a) Your base salary  will be at the annual rate of $62,500,  paid every
two weeks,  subject to withholding  for Federal and state taxes required by law.
We will also pay a signing bonus of $9,000 upon your arrival.

         b) You will  participate  in the  Company's  annual bonus program under
which  bonus  awards at your  level  may  range up to 30% of your  base  salary,
depending on the Company's performance,  the Company's financial condition,  and
other  considerations,  as determined by the Audit and Benefits Committee of the
board of directors.  Bonus plan  objectives are set by the Chairman and ratified
by the Audit and  Benefits  Committee  at their  meeting in December  2001 or in
March 31,  2002.  Plan  revisions  must also be ratified by the  Committee.  The
2000-2001 bonus plan is attached to this letter for information purposes.

         (c) In addition,  the Company will issue you 5,000 shares of restricted
common stock,  $0.01 par value, in accordance with our Stock  Compensation  Plan
(worth  $42,000 at the current  price) and  options  for 5,000  shares of common
stock at an  exercise  price to be set at the fair  market  value at the date of
grant, pursuant to the terms of the 1994 Stock Option Plan, both
<PAGE>

effective as ofthe date of approval by the Audit and  Benefits  Committee of the
board.  You will be eligible to receive  additional  options to purchase  common
stock in  accordance  with the Stock  Option Plan (up to 5,000  shares  annually
under the resolutions of the Audit & Benefit Committee) and additional shares of
restricted stock in accordance with the Stock Compensation Plan.

         (d) You will be  bound by the  Company's  policies  on its core  values
(copy   enclosed),   scientific   misconduct,   lab   safety,   confidentiality,
non-competition,  the  humane  care  and use of  laboratory  animals,  drug-free
workplace,  and other matters. The Company has no fixed working hours;  however,
each employee is encouraged to be present on site during the hours of 10 a.m. to
4 p.m. In connection with our policy of a drug free  workplace,  we are required
by our workers'  compensation  insurance carrier to arrange for a urine test, at
our expense,  on or before your reporting for duty. The urine test will test for
the  presence  of  barbiturates,   amphetamines,   cocaine,  and  certain  other
contraband substances.

         (e) You will be responsible for compliance with the  immigrations  laws
of the United States,  although we will provide  documentation  and will provide
the services of an immigration lawyer at our expense.

         (f) In the event  that you are  terminated  for any  reason  other than
"cause" (gross negligence,  reckless disregard for your duties, or conviction of
a crime involving moral turpitude), we will pay a net severance payment equal to
six months of your then base salary (net of advances, used by unearned vacation,
and any other debts due to the Company), plus reasonable moving expenses back to
Sweden,  and will vest any  unvested  stock  options  or  grants  of  restricted
securities.  Assuming that you are not terminated for cause at any time, and you
are  terminated or resign on or after  December 31, 2002,  then the Company will
enter into a consulting  agreement with you,  terminating on the 4th anniversary
of such  termination  or  resignation.  Such  consulting  agreement  shall be on
mutually agreeable terms.

         (g) The Company has agreed to 25 paid days of  vacation  annually.  The
Company  observes 11 paid holidays  annually.  Ixion has an employee health plan
and  workers'  compensation  insurance,  but no  disability  or  other  employee
benefits.  In the event that the Company's  employee  health plan does not cover
health  expenses  while you or your family are in Sweden during the term of this
agreement, the Company will pay the costs of such insurance,  containing similar
terms as our health  insurance plan,  covering you and your family while you are
overseas.  The Company  does not have a dental  plan,  but will pay the costs of
non-routine  dental  services  for you or your  family  in the  event of  trauma
requiring  dental  care.  We  expect  that we will  have a 401(k)  (savings  and
pension) plan by the anticipated  date of your arrival.  You can accrue up to 12
days of sick leave for each full year of service up to a total of 24 unused days
of sick leave.  Accrued but untaken  vacation  (but not accrued  sick leave) are
paid upon termination.

         (h) We will pay your  reasonable  moving  expenses  upon  submission of
appropriate  supporting  documentation,  and will  purchase  or rent  reasonable
furniture  and  appliances
<PAGE>
for your use  while  you are here if you  elect  not to ship  certain  household
goods.  We will pay for two round-trip  economy class tickets between the United
States and Sweden for each of you and your family members. These tickets are for
your relocation to Ixion to commence employment, your permanent return to Sweden
on or after  December  31,  2002,  and for one round trip for  summer  vacation.
Should  employment  be extended for not less than six months after  December 31,
2002,  then an  additional  round trip to Sweden will be  reimbursed  for use at
Christmas, 2002.

         If the terms of this letter are  acceptable to you,  please execute and
return a copy of this letter by four weeks from the date of this letter.

         I look forward to your arrival.

                                                     Sincerely yours,



                                                     Weaver H. Gaines

Accepted:




Jon Heimer

cc: Kimberly A. Ramsey