Microstructure and properties of nano-fibrous PCL-b-PLLA scaffolds for cartilage tissue engineering

Abstract

Nano-fibrous scaffolds which could potentially mimic the architecture of extracellular matrix (ECM) have been considered a good candidate matrix for cell delivery in tissue engineering applications. In the present study, a semicrystalline diblock copolymer, poly(ε-caprolactone)-block-poly(L-lactide) (PCL-b-PLLA), was synthesized and utilized to fabricate nano-fibrous scaffolds via a thermally induced phase separation process. Uniform nano-fibrous networks were created by quenching a PCL-b-PLLA/THF homogenous solution to -20ºC or below, followed by further gelation for 2 hours due to the presence of PLLA and PCL microcrystals. However, knot-like structures as well as continuously smooth pellicles appeared among the nanofibrous network with increasing gelation temperature. DSC analysis indicated that the crystallization of PCL segments was interrupted by rigid PLLA segments, resulting in an amorphous phase at high gelation temperatures. Combining TIPS (thermally induced phase separation) with saltleaching methods, nano-fibrous architecture and interconnected pore structures (144±36 μm in diameter) with a high porosity were created for in vitro culture of chondrocytes. Specific surface area and protein adsorption on the surface of the nano-fibrous scaffold were three times higher than on the surface of the solid-walled scaffold. Chondrocytes cultured on the nano-fibrous scaffold exhibited a spherical condrocyte-like phenotype and secreted more cartilage-like extracellular matrix (ECM) than those cultured on the solid-walled scaffold. Moreover, the protein and DNA contents of cells cultured on the nanofibrous scaffold were 1.2-1.4 times higher than those on the solid-walled scaffold. Higher expression levels of collagen II and aggrecan mRNA were induced on the nanofibrous scaffold compared to on the solid-walled scaffold. These findings demonstrated that scaffolds with a nanofibrous architecture could serve as superior scaffolds for cartilage tissue engineering.

Alteration of spermatogenesis following spermatogonial stem cells transplantation in testicular torsion-detorsion mice

“…There are various applications of spermatogonial stem cell transplantation beyond basic research [38]. For instance, cancer treatment can cause infertility; thus, obtaining and storing of spermatogonial stem cells from patients could be a promising way to restore and preserve fertility [38][39][40]. Also in testicular torsion, testicular biopsy is likely to provide the spermatogonial stem cells for cryopreservation, storage, and transplantation.…”

Fabrication of a multi-layer three-dimensional scaffold with controlled porous micro-architecture for application in small intestine tissue engineering

“…2), there was a high degree of inter-connectivity between pores and smooth transitions between layers of different porosities, properties that can be easily controlled by the size and quantity of the porogen (e.g., salt crystal in this study; ref. 20). We show the influence of pore size on bridging and penetration by two representative cell types found in tubular or hollow tissues, epithelial, and smooth muscle cells (Figs.…”

Phase Separated Fibrous Structures: Mechanism Study and Applications

“…As a result, the co-polymer systems can self-organize into different complex structures. He et al reported that, with a similar fiber diameter, nano-fibrous structures were obtained at a relative higher T gels in the pure PLLA system than in the PCL-b-PLLA system (39). Polymer crystallization behavior plays an important role in nanofiber formation.…”

“…During the gelation process, the gelation temperature (T gel ) exerts critical influence to the architecture of the resultant scaffolds (38,39). Although all the scaffolds were nanofibrous networks, only the structures of the scaffolds produced at lower temperatures (−40°C and −20°C) were uniform.…”