Osteochondral Tissue Formation Through Adipose-Derived Stromal Cell Differentiation on Biomimetic Polycaprolactone Nanofibrous Scaffolds with Graded Insulin and Beta-Glycerophosphate Concentrations

Abstract

The ability to fabricate tissue engineering scaffolds containing systematic gradients in the distributions of stimulators provides additional means for the mimicking of the important gradients observed in native tissues. Here the concentration distributions of two bioactive agents were varied concomitantly for the first time (one increasing, whereas the other decreasing monotonically) in between the two sides of a nanofibrous scaffold. This was achieved via the application of a new processing method, that is, the twin-screw extrusion and electrospinning method, to generate gradients of insulin, a stimulator of chondrogenic differentiation, and β-glycerophosphate (β-GP), for mineralization. The graded poly(ɛ-caprolactone) mesh was seeded with human adipose-derived stromal cells and cultured over 8 weeks. The resulting tissue constructs were analyzed for and revealed indications of selective differentiation of human adipose-derived stromal cells toward chondrogenic lineage and mineralization as functions of position as a result of the corresponding concentrations of insulin and β-GP. Chondrogenic differentiation of the stem cells increased at insulin-rich locations and mineralization increased at β-GP-rich locations.

Processing of polycaprolactone and hydroxyapatite to fabricate graded electrospun composites for tendon-bone interface regeneration

“…Our group also electrospun PCL and beta tricalcium phosphate (beta-TCP) nanoparticles to generate spatially graded composite meshes for osteochondral (cartilage-bone interface) tissue regeneration applications [11]. Test results confirmed their in vitro cytocompatibility and native-like tissue formation with adipose derived stem cells [12].…”

Cartilage-Bone Interface Features, Scaffold and Cell Options for Regeneration

“…The major ECM components contained in these sub-tissues are collagen type II and glycosaminoglycans; collagen type I, glycosaminoglycans, minerals; and collagen type I and minerals, respectively (Table 1). Another school of thought for the hierarchical organization of the cartilage-bone interface is the belief of graded change in the composition of ECM components [6][7][8][9]. Although the compartmental organization approach for cartilage-bone interface components has been dominant for years [5,10], recent studies characterizing cartilagebone, as well as tendon-bone, interface at microscopic dimensions found that mineral composition is changing gradually across the interface [4,11,12].…”

“…However, recent investigations at micrscopic levels showed that the osteochondral interface exhibits a gradual change in the composition of the matrix components [12], leading to a paradigm shift in the understanding of scaffold design. Therefore, more recent investigations focused on the design and fabrication of graded scaffolds for osteochondral interface applications [6,7,19]. In one of these studies, tricalciumphospate (TCP) mineral was embedded in PCL nanofibers to fabricate scaffolds with gradually changing TCP concentrations [6].…”

“…In one of these studies, tricalciumphospate (TCP) mineral was embedded in PCL nanofibers to fabricate scaffolds with gradually changing TCP concentrations [6]. The same group of researchers produced functionally graded PCL scaffolds incorporated with insulin and betaglyserophospate (beta-GP) biomolecules with varying concentrations in opposite direction [7]. Human adipose derived stem cells (hADSCs) were seeded on the graded scaffolds to form osteochondral-like structures.…”

“…These scaffolds could be designed to contain multiple biomolecules positioned into the scaffold in a controlled fashion, and to release these biofactors in a time-dependent manner to also serve as controlled delivery devices. Such scaffolds were successfully employed for interface regenerative engineering studies both in vitro and in vivo [6,7,28]. These investigations revealed that when the right cells are used in conjunction with an appropriate scaffold and/or scaffold biofactors combination choice, native osteochondral interface could be approximated both biologically and physically.…”