Histology and ultrastructure of a tissue‐engineered collagen meniscus before and after implantation

Abstract

The collagen meniscus implant (CMI) is a tissue-engineering technique designed to stimulate regeneration of meniscus-like tissue in cases of irreparable tears or previous meniscectomy. CMI morphology was investigated before and after implantation by light microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). In a case series biopsy specimens were harvested from four patients who underwent a second arthroscopic look 6 months after placement of the CMI. CMI sections appeared composed of parallel connective laminae of 10-30 microm, connected by smaller bundles (5-10 microm). This connective network formed lacunae with diameters between 40 and 60 microm. At greater magnification, the walls of the lacunae demonstrated tightly packed and randomly distributed collagen fibrils, with diameters ranging from 73 to 439 nm. In the biopsy specimens, the lacunae were filled with connective tissue that contained newly formed vessels and fibroblast-like cells, presenting an abundant rough endoplasmic reticulum and several mitochondria. In the extracellular matrix, the collagen fibrils showed uniform diameters (126 nm +/- 32 nm). The original structure of CMI was still recognizable, and no inflammatory cells were detected within the implant. The morphological findings of this case series demonstrate that CMI provides a three-dimensional scaffold suitable for colonization by precursor cells and vessels and leading to the formation of a fully functional tissue.

The magnetic resonance aspect of a polyurethane meniscal scaffold is worse in advanced cartilage defects without deterioration of clinical outcomes after a minimum two-year follow-up

“…Conversely, the size and morphology of the polyurethane meniscal scaffold were better preserved (Genovese 3) in the current as well as in a previous study [6]. However, the composition of the Actifit® and thus its degradation rate are completely different from the CMI® [17,18]. Thus, a two-years follow-up might still be too short to conclude any advantage.…”

Investigation of the Regenerative Capacity of an Acellular Porcine Medial Meniscus for Tissue Engineering Applications

“…Clinical findings have been inconclusive with regard to chondroprotection. [25][26][27][28][29] A key choice in the development of a tissue-engineered implant is whether to engineer a cellularized construct. [29][30][31][32][33][34][35][36] Cellularized scaffolds may be particularly important when the cells are necessary for maintenance of the surrounding matrix or have an important function, for example, preservation of the antithrombogenicity of a vascular conduit via endothelization or simply to aid continual growth in young recipients.…”

Development and Characterization of an Acellular Porcine Medial Meniscus for Use in Tissue Engineering

“…In vivo results have been promising with human meniscal cartilage-like tissue growing into the collagen scaffold. 1,[11][12][13][14][15] However, initial biomechanics of the CMI are known to be poor. 16 This has been attributed to the random orientation of the CMI collagen fibers, which prevents the applied load being converted into circumferentially directed forces and associated hoop tensile stresses which are usually restrained by the circumferential collagen fibers found in native menisci.…”