A volume-stable collagen matrix promotes osteogenesis and osteoinduction in cleft lip fibroblasts: A novel approach for alveolar cleft repair

The resorbability of a volume stable collagen matrix (vsCM) used for soft tissue augmentation makes it an appealing scaffold for bone tissue engineering in the craniofacial area, for example when congenital maxillary bone deficiencies occur in patients born with a cleft lip with or without palate. Hence, this study aimed to evaluate the bioactivity and biocompatibility of a vsCM using fibroblasts (CL-Fb) isolated from discarded lip tissues obtained during cheiloplasty, which exhibit strong bone differentiation potential in vitro. We first characterized the physical and biochemical properties of the vsCM, confirming that its porosity closely resembles alveolar bone, with pore sizes between 50 and 100 µm. The matrix showed a high affinity for fibronectin, a serum protein critical for activating key osteogenic signaling pathways. Adsorption analyses revealed that up to 80 % and 45 % of human and bovine fibronectin, respectively, present in 200 µl of their respective 10 % serum, were bound by a vsCM sample measuring 3 mm in height and 4 mm in diameter. Following ISO 10993 guidelines, biocompatibility assays demonstrated that the vsCM supports CL-Fb viability, migration, and proliferation. It also promoted CL-Fb osteogenic differentiation and bone morphogenetic proteins (BMP) production, thereby activating autocrine and paracrine BMP/SMAD signaling to foster a regenerative microenvironment. These findings provide the first evidence supporting vsCM as a candidate for bone regeneration applications and lay the groundwork for future in vivo validation.