H&E staining of SF, A-SF, SF-nHAp and A-SF-nHAp films seeded with MSCs in subcutaneously implanted rat model after 4 weeks. Yellow arrows indicated the new vessels. Well-organized MSCs, a small number of neutrophils and some new vessels were observed around all films, suggesting a mild inflammatory response and good biocompatibility of SF, SF-nHAp, A-SF and A-SF-nHAp films. SF: pristine SF film; A-SF: air-plasma-treated SF film; SF-nHAp: SF film with mineralized nHAp; A-SF-nHAp: A-SF film with mineralized nHAp; M: implanted materials.