Abstract
Collagen meniscus implant (CMI) is a tissue engineering technique for the management of irreparable meniscal lesions. In this study we evaluate morphological and biochemical changes occurring in CMI after implantation. Gene expression technique was also adopted to characterise the phenotype of the invading cells.
Light microscopy, immunohistochemistry (type I and II collagen), SEM and TEM analysis were performed on five biopsy specimens harvested from five different patients (range, 6 to 16 months after surgery). Fluorophore-assisted carbohydrate electrophoresis (FACE) and real-time PCR evaluation were carried out on two biopsy specimens harvested 6 and 16 months, respectively, after implantation. All these investigations were also applied on non-implanted scaffolds for comparison.
Scaffold sections appeared to be composed of parallel connective laminae, connected by smaller connective bundles surrounding elongated lacunae. In the biopsy specimens, the lacunae were filled by connective tissue with newly formed vessels and fibroblast-like cells. Immunohistochemistry revealed exclusively type I collagen in the scaffold, while type II collagen appeared in the biopsy specimens. FACE analysis carried out in the scaffold did not detect any GAG disaccharides. Conversely, disaccharides were detected in the implants. Real-time PCR showed a signal only for collagen type I. In the scaffolds no gene expression was recorded.
The morphological findings demonstrate that CMI is a biocompatible scaffold available for colonisation by connective cells and vessels. Biochemical data show a specific production of extracellular matrix after implantation. The absence of signal for type II collagen gene can be attributed to different maturation stages of the in-growing tissue.
