As filed with the Securities and Exchange Commission on November 27, 2023. Registration No. 333-275361 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Amendment No. 1 to FORM S-1 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 FibroBiologics, Inc. (Exact name of registrant as specified in its charter) Delaware 2834 86-3329066 (State or other jurisdiction of incorporation or organization) (Primary Standard Industrial Classification Code Number) (I.R.S. Employer Identification ...