A living thick nanofibrous implant bifunctionalized with active growth factor and stem cells for bone regeneration

Abstract

New-generation implants focus on robust, durable, and rapid tissue regeneration to shorten recovery times and decrease risks of postoperative complications for patients. Herein, we describe a new-generation thick nanofibrous implant functionalized with active containers of growth factors and stem cells for regenerative nanomedicine. A thick electrospun poly(ε-caprolactone) nanofibrous implant (from 700 μm to 1 cm thick) was functionalized with chitosan and bone morphogenetic protein BMP-7 as growth factor using layer-by-layer technology, producing fish scale-like chitosan/BMP-7 nanoreservoirs. This extracellular matrix-mimicking scaffold enabled in vitro colonization and bone regeneration by human primary osteoblasts, as shown by expression of osteocalcin, osteopontin, and bone sialoprotein (BSPII), 21 days after seeding. In vivo implantation in mouse calvaria defects showed significantly more newly mineralized extracellular matrix in the functionalized implant compared to a bare scaffold after 30 days’ implantation, as shown by histological scanning electron microscopy/energy dispersive X-ray microscopy study and calcein injection. We have as well bifunctionalized our BMP-7 therapeutic implant by adding human mesenchymal stem cells (hMSCs). The activity of this BMP-7-functionalized implant was again further enhanced by the addition of hMSCs to the implant (living materials), in vivo, as demonstrated by the analysis of new bone formation and calcification after 30 days’ implantation in mice with calvaria defects. Therefore, implants functionalized with BMP-7 nanocontainers associated with hMSCs can act as an accelerator of in vivo bone mineralization and regeneration.

Bone substitutes: a review of their characteristics, clinical use, and perspectives for large bone defects management

“…Polyesters like poly(ε-caprolactone) (PCL), for example, can be synthetized by mimicking the collagenic matrix, offering a structural porosity and osteoconductive properties. 136 , 137 Most of the polymer-based bone substitutes are suitable to be used as bioactive molecules or growth factors carriers, 138 potentially conferring osteogenetic properties. 139 Since PCL is soluble in a wide range of organic solvents, it is a promising polymer for continuous researches in tissue engineering.…”

“…PCL or PLA). 136 , 138 Clinicians should keep a close eye on outcomes of researches concerning polymer-based bone substitutes as scaffolds for regenerative medicine.…”

Maxillary Bone Regeneration Based on Nanoreservoirs Functionalizedε-Polycaprolactone Biomembranes in a Mouse Model of Jaw Bone Lesion

“…There are many perspectives and potential therapeutic clinical applications, like functionalization with mesenchymal stem cells or osteoblasts, use of different BMP isoforms homodimeric and heterodimeric associations [ 9 , 10 ], or different molecules like statins or hypoxia-mimetic agents [ 42 ]. Experimental use of these molecules was already reported, but with other types of scaffolds like hydrogels [ 43 ] or in gelatin nanofibrous scaffold [ 41 ].…”

“…Thus, nanofibers promote osteoblast adhesion [ 6 ], proliferation [ 7 ], differentiation [ 8 ], and biomineralization [ 6 ]. In vivo , electrospun matrices of poly( ε -caprolactone) (PCL) showed favorable results for bone regeneration [ 9 – 11 ].…”

“…It allows the concentration of many different functions in a small volume and presents the advantage of increasing the quality of targeting while controlling the cost and delivery kinetics of the active molecules [ 12 ]. Thus, the strategy of functionalization of nanofibers by nanoreservoirs of BMP-2 or BMP-7 showed a great efficiency for bone regeneration and increased the differentiation of MSCs (mesenchymal stem cells), accelerating the tissue regeneration in vivo [ 9 , 10 , 13 , 14 ]. These different nanofiber scaffolds with nanoreservoirs are efficient proregenerative biomimicking implants for bone regeneration.…”