Adipose Stem Cells from Buccal Fat Pad and Abdominal Adipose Tissue for Bone tissue Engineering

Abstract

ABSTRACT Background and Objective: Stem cells offer an interesting tool for tissue engineering, but the clinical applications are limited by donor site morbidity and low cell number upon harvest. Recent studies have identified an abundant source of stem cells in subcutaneous adipose tissue. These adipose stem cells (ASC), are able to differentiate to several lineages and express multiple growth factors, which makes them suitable for clinical application. Buccal fat pad (BFP), an adipose encapsulated mass in the oral cavity, could represent an easy access source for dentists and oral surgeons. Biosynthetic substitutes such as β-tricalcium phosphate (β-TCP), hydroxyapatite (HA), and mixtures of HA/β-TCP (biphasic calcium phosphate; BCP) have been successfully used as bone graft biomaterials. Growth factors stimulating osteogenic differentiation are also interesting for bone tissue engineering applications. We aimed to investigate whether BFP is a rich source of ASC, and whether ASC triggered for only 15 min with bone morphogenetic protein-2 (BMP-2), and seeded onto different calcium phosphate scaffolds composed of β-TCP alone or mixtures of HA/β-TCP, could stimulate bone formation. Materials & Methods: ASC obtained from subcutaneous abdominal adipose tissue and BFP were counted and analyzed by flow cytometry, to determine ASC cell number, phenotype and percentage. At two weeks of culture, the multipotent differentiation potential of ASC from BFP was analyzed. Furthermore, fresh ASC either or not stimulated with 10ng/ml BMP-2 for 15min were seeded on different calcium phosphate scaffolds. ASC attachment, proliferation and osteogenic differentiation was analyzed and compared. Results: BFP contained ~30% of ASC. The ASC number obtained per gram of adipose tissue from BFP at one week of culture was 2-fold higher than in subcutaneous abdominal adipose tissue. Angiogenic marker expression was also higher, and ASC showed multipotent differentiation potential as well. Fifteen min BMP-2 treatment increased ASC cell proliferation and osteogenic differentiation on BCP composed of 60% HA and 40% β-TCP, but not on other scaffolds containing less percentage of HA. Conclusions: Buccal fat pad is a rich alternative source of ASC suitable for bone tissue engineering. Short stimulation of only 15 minutes with BMP-2 is enough to stimulate ASC proliferation and osteogenic differentiation. Therefore ASC could be treated shortly with BMP-2 and seeded on BCP with 60% HA to improve bone regeneration.