912. Accelerated Chondrogenesis in Nanofiber Scaffolds Containing BMP-2 Genetically Engineered Chondrocytes

Articular cartilage injury and erosion is a common cause of joint pain often leading to osteoarthritis and permanent morbidity. This research sought to determine if genetically engineered chondrocytes can sustain chondrogenesis in a biodegradable nanofiber scaffold. We hypothesized that chondrocytes would adhere, seed, proliferate, and produce extracellular matrix proteins typical of articular cartilage within a polycaprolactone nanofiber scaffold and this would be accelerated and more robust with hBMP-2 genetically engineered cells. Equine chondrocytes were seeded onto electrospun polycaprolactone nanofiber sheets of 150-200μm thickness and 10μm pore size and cultured in Snapwell plates across a serum gradient of 10% or 30% FBS for 2, 7, 14 and 21 days at 0.5, 1.0, and 1.5 × 106 cells/ml density. Best chondrocyte penetration into the scaffold was achieved with 1 × 106 cell seeding density and 30% serum gradient in which cells on the surface at day 2 penetrated 3/4 into the scaffold by day 7.Using these conditions, chondrocytes were cultured in triplicate either untreated, transduced with Adenoviral [Ad]-GFP, or transduced with Ad-human (h) bone morphogenetic protein (BMP)-2 for 14 days. Constructs were quantitatively evaluated for cell proliferation (DNA [ug/ml]), % viability (confocal microscopy), and matrix expression (proteoglycan (ng/ml), aggrecan (ddCT), collagen 1 (ddCT), and collagen II (ddCT). Using equine specific primers and probes, mRNA levels were expressed as ratios to 18Srna and to controls (ddCT; Fig 2). BMP-2 production and transduction efficiency (%GFP+ cells) were compared. Viable cells (>90%) and high transduction efficiency (>80%) were confirmed within the biodegradable three-dimensional nanofiber scaffold using confocal and scanning electron microscopy. Accelerated and more robust expression and production of BMP-2, aggrecan and collagen II, and to a lesser extent collagen 1, persisted in the AdBMP2 treated chondrocytes within the scaffold.Use of nanofiber scaffolds to culture chondrocytes is novel and yielded a cell-supporting, biocompatible, and biodegradable tissue- and genetically-engineered construct for potential use in one-step articular cartilage repair in vivo.