Microsphere-based scaffolds for cartilage tissue engineering: Using subcritical CO2 as a sintering agent

Abstract

Shape-specific, macroporous tissue engineering scaffolds were fabricated and homogeneously seeded with cells in a single step. This method brings together CO 2 polymer processing and microparticle-based scaffolds in a manner that allows each to solve the key limitation of the other. Specifically, microparticle-based scaffolds have suffered from the limitation that conventional microsphere sintering methods (e.g., heat, solvents) are not cytocompatible, yet we have shown that cell viability was sustained with sub-critical (i.e., gaseous) CO 2 sintering of microspheres in the presence of cells at near-ambient temperatures. On the other hand, the fused microspheres provided the pore interconnectivity that has eluded supercritical CO 2 foaming approaches. Here, fused poly (lactide-co-glycolide) microsphere scaffolds were seeded with human umbilical cord mesenchymal stromal cells to demonstrate the feasibility of utilizing these matrices for cartilage regeneration. We also demonstrated that the approach may be modified to produce thin cell-loaded patches as a promising alternative for skin tissue engineering applications.

Design of controlled release systems for THEDES—Therapeutic deep eutectic solvents, using supercritical fluid technology

“…The softening of the polymer under a CO 2 atmosphere allows the sintering of the particles, promoting their adhesion while leaving empty pores inside the formed structure. Supercritical fluid sintering has been described in the literature for the preparation of different scaffolds, particularly for tissue engineering, and it is particularly attractive due to the mild operating conditions, which allow the processing of thermolabile substances (Bhamidipati et al, 2013;Singh et al, 2010). The main objective of this work was the development of a controlled delivery system based on a starch polymer blend impregnated with menthol:ibuprofen THEDES, obtained by supercritical fluid sintering.…”

“…CO 2 is the most commonly used solvent at supercritical conditions due to its low critical parameters (T c = 31.1 C and P c = 73.8 bar) and to the fact that it is environmentally benign, non-toxic, non-flammable, non-corrosive, readily available and inexpensive. Supercritical fluid sintering was proposed by Singh et al (2010) for the preparation of highly porous and interconnected structures, under mild conditions. The supercritical sintering technique, similarly to supercritical fluid foaming, relies on the plasticizing effect of CO 2 , which reduces the glass transition temperature (T g ) of the polymer.…”

From solvent-free microspheres to bioactive gradient scaffolds

“…This method enables high level control over the pore size distribution through the scaffold. Although microsphere sintering has been employed to fabricate various 3D scaffolds, [19][20][21][22][23][24][25] creating solvent-free scaffolds with pore size gradient based on this method has not been previously reported. Our results demonstrate that using such a method, a perfect control over the scaffold architecture could be simply, reproducibly and cheaply achieved.…”

Reparation of chondral defects in rabbits by autologous and allogenous chondrocytes seeded on collagen/hyaluronan scaffold or suspended in fibrin glue

“…Therefore, the culturing period of chondrocytes for one month was chosen in our study. Different scaffolds were used as cell or tissue carriers for cartilage tissue engineering so far [20][21][22][23]. The major advantage of collagen scaffolds, which were used in our experiment, is their tissue abundance and a highly organized structure.…”