Cartilage reconstruction in head and neck surgery: Comparison of resorbable polymer scaffolds for tissue engineering of human septal cartilage

Abstract

New cell culture techniques raise the possibility of creating cartilage in vitro with the help of tissue engineering. In this study, we compared two resorbable nonwoven cell scaffolds, a polyglycolic acid/poly-L-lactic acid (PGA/PLLA) (90/10) copolymer (Ethisorb) and pure PLLA (V 7-2), with different degradation characteristics in their aptitude for cartilage reconstruction. Chondrocytes were isolated enzymatically from human septal cartilage. The single cells were resuspended in agarose and transferred into the polymer scaffolds to create mechanical stability and retain the chondrocyte-specific phenotype. The cell-polymer constructs were then kept in perfusion culture for 1 week prior to subcutaneous transplantation into thymusaplastic nude mice. After 6, 12, and 24 weeks, the specimens were explanted and analyzed histochemically on the presence of collagen (azan staining), proteoglycans (Alcian blue staining), and calcification areas (von Kossa staining). Furthermore, different collagen types (collagen type I, which is found in most tissues, but not in hyaline cartilage matrix; and collagen type II, which is cartilage specific) were differentiated immunohistochemically by the indirect immunoperoxidase technique. Vascular ingrowth was investigated by a factor VIII antibody, which is a endothelial marker. Quantification of several matrix components was performed using the software Photoshop. Significant differences were found between both nonwoven structures concerning matrix synthesis and matrix quality as well as vascular ingrowth. Ethisorb, with a degradation time of approximately 3 weeks in vitro, showed no significant differences from normal human septal cartilage in the amount of collagen types I and II 24 weeks after transplantation. Thin fibrous tissue layers containing blood vessels encapsulated the transplants. V 7-2 constructs, which did not show strong signs of degradation even 24 weeks after transplantation, contained remarkably smaller amounts of cartilage-specific matrix components. At the same time, there was vascular ingrowth even in central parts of the transplants. In conclusion, polymer scaffolds with a short degradation time are suitable materials for the development of cartilage matrix products, while longer stability seems to inhibit matrix synthesis. Thus, in vitro engineering of human cartilage can result in a cartilage-like tissue when appropriate nonwovens are used. Therefore, this method could be the ideal cartilage replacement method without the risk of infection and with the possibility of reconstructing large defects with different configurations.

Gelatin-based resorbable sponge as a carrier matrix for human mesenchymal stem cells in cartilage regeneration therapy

“…com to focal lesions such as those that often occur after traumatic injury to cartilage is to combine the cells with a biomatrix that serves to deliver the cells and to retain them at the delivery site. A variety of materials has been investigated as biomatrices, including collagens and collagen derivatives, 14,22,23 polymers, such as polylactic acid (PLA) and polyglycolic acid (PGA), and their copolymers, [24][25][26][27] and hyaluronan derivatives. 28,29 Among the essential characteristics of an ideal biomatrix for MSC-based cartilage regeneration therapy are biocompatibility at the implant site and its ability to support chondrogenesis.…”

Proliferating Cells versus Differentiated Cells in Tissue Engineering

“…In analogy cells are cultured on an artificial extracellular matrix in tissue engineering. [7][8][9] In vitro development of functional tissues as used for cartilage repair or for the development of liver modules can only be expected when both components interact in an optimal manner. The goal in tissue engineering is to generate tissue specific features while avoiding atypical protein expression, caused by suboptimal culture conditions and cellular dedifferentiation.…”

“…It is unknown though how being exposed to the obviously identical environment of an organ-for example, the villous epithelium of small intestine displays a high proliferative capacity while EC and Paneth cell populations within the crypts remain in the interphase. Chondroblasts and osteoblasts proliferate rapidly, 6,8,9 while matrix-producing osteocytes do not divide.…”

Bioresorbable Polymers for Tissue Engineering

“…On the other hand, cells grown on PLLA scaffolds presented a greater capacity of synthesizing type I collagen [60]. Interesting results were also obtained with PLLA scaffolds used for meniscus reconstruction.…”