X0306 4 2023-02-23 0 0001383701 Histogen Inc. HSTO 0001580465 Spada Alfred P. C/O HISTOGEN INC. 10655 SORRENTO VALLEY ROAD, SUITE 200 SAN DIEGO CA 92121 0 1 0 0 See Remarks Stock Option (right to buy) 1.041 2023-02-23 4 A 0 106793 0.00 A 2033-02-23 Common Stock 106793 106793 D This option was issued to the Reporting Person as an inducement to employment with the Issuer. It is intended to be an inducement grant in accordance with Rule 5635(c)(4) of the Nasdaq Listing Rules. 1/4 of the shares subject to the option vest one year after the date of grant, on 2/1/2024, and the remaining 1/36 of the shares vest on a monthly basis thereafter. Executive Vice President and Chief Scientific Officer /s/ Susan A. Knudson as attorney-in-fact for Alfred P. Spada, Ph.D. 2023-02-27