Osiris Therapeutics 10-K 2010 FY Annual report

Exhibit 4.1

NUMBER 0 02007 SHARES VOID Osiris* THERAPEUTICS, INC. SEE REVERSE FOR INCORPORATED UNDER THE LAWS OF THE STATE OF MARYLAND CERTAIN DEFINITIONS COMMON STOCK CUSIP 68827R 10 8 THIS CERTIFIES THAT: IS THE OWNER OF VOID FULLY PAID AND NON-ASSESSABLE SHARES OF COMMON STOCK OF $.001 PAR VALUE EACH OF OSIRIS THERAPEUTICS, INC. transferable on the books of the Corporation in person or by duly authorized attorney upon surrender of this certificate duly endorsed or assigned. This certificate and the shares represented hereby are subject to the laws of the Corporation, as now or hereafter amended. This certificate is not valid until countersigned by the Transfer Agent. WITNESS the facsimile seal of the Corporation and the facsimile signatures of its duly authorized officers. DATED: COUNTERSIGNED: STOCKTRANS, A BROADRIDGE COMPANY 44 WEST LANCASTER AVE., ARDMORE, PA 19003 TRANSFER AGENT BY: AUTHORIZED SIGNATURE SECRETARY & CFO PRESIDENT & CEO OSIRIS THERAPEUTICS, INC. CORPORATE SEAL 2010 MARYLAND

The following abbreviations, when used in the inscription on the face of this certificate, shall be construed as though they were written out in full according to applicable laws or regulations: TEN COM - as tenants in common UNIF GIFT MIN ACT- Custodian TEN ENT - as tenants by the entireties (Cust) (Minor) JT TEN - as joint tenants with right of under Uniform Gifts to Minors survivorship and not as tenants Act in common (State) Additional abbreviations may also be used though not in the above list. For Value Received, hereby sell, assign and transfer unto PLEASE INSERT SOCIAL SECURITY OR OTHER IDENTIFYING NUMBER OF ASSIGNEE (PLEASE PRINT’ OR TYPE NAME AND ADDRESS, INCLUDING ZIP CODE, OF ASSIGNEE) Shares of the stock represented by the within Certificate, and do hereby irrevocably constitute and appoint Attorney to transfer the said stock on the books of the within named Corporation with full power of substitution in the premises. Dated NOTICE: THE SIGNATURE TO THIS ASSIGNMENT MUST CORRESPOND WITH THE NAME AS WRITTEN UPON THE FACE OF THE CERTIFICATE IN EVERY PARTICULAR, WITHOUT ALTERATION OR ENLARGEMENT OR ANY CHANGE WHATSOEVER. THE SIGNATURE TO THE ASSIGNMENT MUST CORRESPOND TO THE NAME AS WRITTEN UPON THE FACE OF THIS CERTIFICATE IN EVERY PARTICULAR, WITHOUT ALTERATION OR ENLARGEMENT OR ANY CHANGE WHATSOEVER, AND MUST BE GUARANTEED BY A COMMERCIAL BANK OR TRUST COMPANY OR A MEMBER FIRM OF A NATIONAL OR REGIONAL OR OTHER RECOGNIZED STOCK EXCHANGE IN CONFORMANCE WITH A SIGNATURE GUARANTEE MEDALLION PROGRAM. COLUMBIA FINANCIAL PRINTING CORP. - www.stockinformation.com