Perlecan in the Natural and Cell Therapy Repair of Human Adult Articular Cartilage: Can Modifications in This Proteoglycan Be a Novel Therapeutic Approach?

Jan Herman Kuiper,Sally Roberts,Helen S Mccarthy,John Garcia,James Melrose

doi:10.3390/biom11010092

Abstract

Articular cartilage is considered to have limited regenerative capacity, which has led to the search for therapies to limit or halt the progression of its destruction. Perlecan, a multifunctional heparan sulphate (HS) proteoglycan, promotes embryonic cartilage development and stabilises the mature tissue. We investigated the immunolocalisation of perlecan and collagen between donor-matched biopsies of human articular cartilage defects (n = 10 × 2) that were repaired either naturally or using autologous cell therapy, and with age-matched normal cartilage. We explored how the removal of HS from perlecan affects human chondrocytes in vitro. Immunohistochemistry showed both a pericellular and diffuse matrix staining pattern for perlecan in both natural and cell therapy repaired cartilage, which related to whether the morphology of the newly formed tissue was hyaline cartilage or fibrocartilage. Immunostaining for perlecan was significantly greater in both these repair tissues compared to normal age-matched controls. The immunolocalisation of collagens type III and VI was also dependent on tissue morphology. Heparanase treatment of chondrocytes in vitro resulted in significantly increased proliferation, while the expression of key chondrogenic surface and genetic markers was unaffected. Perlecan was more prominent in chondrocyte clusters than in individual cells after heparanase treatment. Heparanase treatment could be a means of increasing chondrocyte responsiveness to cartilage injury and perhaps to improve repair of defects.

Highlights

Cell morphology was marginally better in the cell therapy repaired biopsies, but not significantly different to the naturally repaired biopsies
We demonstrate that the heparan sulphate (HS) proteoglycan, perlecan, is clearly present in repair tissue formed both via cell therapy repair of chondral defects and naturally occurring repair tissue
The localisation of perlecan, as well as type III collagen, which is often found in developing or repairing tissue, is more diffuse for both molecules in the fibrocartilaginous tissue which forms initially, than in the more mature repair tissue. This more mature repair tissue has morphology resembling hyaline cartilage with has more of the typical cell-associated staining pattern seen in adult articular cartilage

Summary

Introduction

Articular cartilage can withstand compressive, tensile and shear loading and provides efficient articulation of diarthrodial joints. If left untreated, damaged articular cartilage in a joint can lead to osteoarthritis (OA) and joint failure [1,2]. Cell-based therapies have been developed to promote cartilage repair and the regeneration of complex articular structure to help patients with damaged or degenerate cartilage [3,4]. It is commonly reported that adult articular cartilage has a limited capacity for selfregeneration [5]; a growing body of evidence from in vitro and in vivo models suggests that in some cases, cartilage can undergo some form of natural repair [6,7].

Methods

Results

Discussion

Conclusion