Exhibit 10.1

FIRST AMENDMENT TO AGREEMENT AND PLAN OF MERGER

This FIRST AMENDMENT TO AGREEMENT AND PLAN OF MERGER (this “Amendment”), dated
as of January 29, 2014, is by and among Intrexon Corporation, a Virginia
corporation (“Parent”), XON Cells, Inc., a Nevada corporation and a wholly owned
subsidiary of Parent (“Merger Sub”), and Medistem Inc., a Nevada corporation
(the “Company”).

WHEREAS, Parent, Merger Sub and the Company are parties to that Agreement and
Plan of Merger, dated as of December 19, 2013 (the “Agreement”);

WHEREAS, Parent, Merger Sub and the Company desire to amend the Agreement on the
terms and conditions set forth herein;

WHEREAS, Section 7.3 of the Agreement provides that: (i) the Agreement may be
amended by the parties by action taken by or on behalf of their respective
Boards of Directors at any time prior to the Closing Date; provided, however,
that, after approval of the Merger by the stockholders of the Company, no
amendment may be made that, by Law or in accordance with the rules of any
relevant stock exchange, requires further approval by such stockholders; and
(ii) the Agreement may not be amended except by an instrument in writing signed
by the parties hereto; and

WHEREAS, the respective Boards of Directors of the parties to the Agreement have
approved this Amendment prior to the approval of the Merger by the stockholders
of the Company.

NOW, THEREFORE, in consideration of the foregoing and the respective
representations, warranties, covenants and agreements set forth below and for
other good and valuable consideration, the receipt and sufficiency of which are
hereby acknowledged, the parties hereto, intending to be legally bound, do
hereby agree as follows:

 

  1. Definitions. Capitalized terms used and not otherwise defined herein
(including in the recitals hereto) shall have the meanings given to them in the
Agreement.

 

  2. Amendments.

 

  a. A new Section 5.17 is hereby added to the Agreement to read as follows:

“Section 5.17. If, prior to the Closing, there are any Company Stockholders who
have properly exercised and preserved dissenters’ rights and such exercise has
not been withdrawn or otherwise satisfied immediately prior to the Effective
Time, then, immediately following the Effective Time of the Merger, Parent shall
cause the Surviving Corporation to merge, in accordance with applicable Law,
with and into a limited liability company and wholly owned subsidiary of Parent
(“Second Merger Sub”), with Second Merger Sub surviving such merger (the
“Subsequent Merger”). For these purposes, the parties hereby confirm that it is
intended that the Merger and the Subsequent Merger constitute an integrated plan
of the type contemplated in IRS Revenue Ruling 2001-46, 2001-2 C.B. 321 (the
“Integrated Transaction”) and that in the event that the Integrated Transaction
is to qualify as a “reorganization” within the

--------------------------------------------------------------------------------

meaning of Section 368(a) of the Code, and the regulations promulgated
thereunder, then the parties intend for this Agreement to constitute a plan of
reorganization within the meaning of Section 368(a) of the Code for U.S. federal
income Tax purposes. The parties further acknowledge and agree that in no way
shall such restructuring result in any change in the Cash Consideration, the
Stock Consideration, the Merger Consideration or in the economics or other
material terms of the transactions contemplated by this Agreement to the Company
or its stockholders, or Parent, Merger Sub or their shareholders and
stockholders, respectively.”

 

  b. The reference to “Section 5.7(e)” in the last sentence of Section 5.7(d) of
the Agreement is hereby amended to be a reference to “Section 5.7(f)”.

 

  3. Effect of Amendment. The provisions of the Agreement are amended and
modified by the provisions of this Amendment. If any provision of the Agreement
is materially different from or inconsistent with any provision of this
Amendment, the provision of this Amendment shall control, and the provision of
the Agreement shall, to the extent of such difference or inconsistency, be
disregarded.

 

  4. Single Agreement. This Amendment and the Agreement, as amended and modified
by the provisions of this Amendment, shall constitute and shall be construed as
a single agreement. The provisions of the Agreement, as amended and modified by
the provisions of this Amendment, are incorporated herein by this reference and
are ratified and affirmed. The term “Agreement” as used in the Agreement shall
be deemed to refer to the Agreement as amended hereby.

 

  5. Headings. The underlined headings herein are for convenience only and shall
not affect the interpretation of this Amendment.

 

  6. Governing Law. This Amendment shall be governed by, and construed in
accordance with, the Laws of the State of New York (including sections 5-1401
and 5-1402 of the New York General Obligations Law but excluding all other
choice of law and conflicts of law rules), except to the extent that mandatory
provisions of federal Law apply or mandatory principles of Law require the
application of the NRS.

 

  7. Counterparts. This Amendment may be executed in one or more counterparts,
and by the different parties hereto in separate counterparts, each of which when
executed shall be deemed to be an original but all of which taken together shall
constitute one and the same agreement.

 

  8. Entire Agreement. The Agreement, as amended and modified by this Amendment,
constitutes the entire agreement between the parties with respect to the subject
matter of this Agreement and supersedes all prior agreements and understandings,
both oral and written, between the parties with respect to its subject matter.

{Signature Page to Follow}

--------------------------------------------------------------------------------

IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be executed
as of the date first written above by their respective officers thereunto duly
authorized.

 

INTREXON CORPORATION By:  

/s/ Randal J. Kirk

  Name: Randal J. Kirk   Title: Chief Executive Officer XON CELLS, INC. By:  

/s/ Randal J. Kirk

  Name: Randal J. Kirk   Title: President MEDISTEM INC. By:  

/s/ Alan J. Lewis

  Name: Alan J. Lewis, Ph.D.   Title: Chief Executive Officer