The effect of the addition of adipose-derived mesenchymal stem cells to a meniscal repair in the avascular zone: an experimental study in rabbits

Cartilage restoration in haemophilia: advanced therapies

Current treatment of joint cartilage lesions is based either on conventional techniques (bone marrow stimulation, osteochondral autograft or allograft transplantation) or on newly developed techniques (chondrocyte implantation and those based on cell therapy that use bioreactors, growth factors, mesenchymal stem cells [MSCs] and genetically modified cells). The aim of this article is to review the therapeutic strategies above mentioned and to determine whether the chondral damage seen in haemophilia could benefit from any of them. The different conventional techniques have shown similar results whereas autologous chondrocyte implantation, which is in common use at the present time, has not been shown to produce any conclusive results or to lead to the formation of hyaline cartilage. MSCs hold promise for the repair of joint cartilage given their differentiation capacity and the therapeutic effect. The use of bioreactors and growth factors, which stimulate cartilage formation, may optimize such strategies in the context of reimplantation of chondrocytes, differentiated MSCs and cartilage progenitor cells. The aim of cell therapy is restoration of function through the repair of damaged tissue or the stimulation of growth factor synthesis. Implantation of autologous chondrocytes or MSCs was up to now able to address only highly localized chondral lesions. Adequate control of the differentiation process as well as the use of growth factors and appropriate bioreactors could transform cell-based therapies into a more efficient and longer term treatment even for patients with haemophilia. Nevertheless, raising false expectations in these patients should be avoided. There are a number of approaches to cartilage restoration in haemophilic arthropathy, which are currently being explored for other joint related degenerative disorders. If it can be proven to be effective for the disorders in which clinical trials are ongoing and costs could be limited, it might be an useful palliative approach to haemophilic arthropathy. However, we still have a long way to go for use in haemophilic arthropathy.

Interleukin-1, tumor necrosis factor-alpha, and transforming growth factor-beta 1 and integrative meniscal repair: influences on meniscal cell proliferation and migration

Introduction

Interleukin-1 (IL-1) and tumor necrosis factor-α (TNF-α) are up-regulated in injured and osteoarthritic knee joints. IL-1 and TNF-α inhibit integrative meniscal repair; however, the mechanisms by which this inhibition occurs are not fully understood. Transforming growth factor-β1 (TGF-β1) increases meniscal cell proliferation and accumulation, and enhances integrative meniscal repair. An improved understanding of the mechanisms modulating meniscal cell proliferation and migration will help to improve approaches for enhancing intrinsic or tissue-engineered repair of the meniscus. The goal of this study was to examine the hypothesis that IL-1 and TNF-α suppress, while TGF-β1 enhances, cellular proliferation and migration in cell and tissue models of meniscal repair.

Methods

A micro-wound assay was used to assess meniscal cell migration and proliferation in response to the following treatments for 0, 24, or 48 hours: 0 to 10 ng/mL IL-1, TNF-α, or TGF-β1, in the presence or absence of 10% serum. Proliferated and total cells were fluorescently labeled and imaged using confocal laser scanning microscopy and the number of proliferated, migrated, and total cells was determined in the micro-wound and edges of each image. Meniscal cell proliferation was also assessed throughout meniscal repair model explants treated with 0 or 10 ng/mL IL-1, TNF-α, or TGF-β1 for 14 days. At the end of the culture period, biomechanical testing and histological analyses were also performed. Statistical differences were assessed using an ANOVA and Newman-Keuls post hoc test.

Results

IL-1 and TNF-α decreased cell proliferation in both cell and tissue models of meniscal repair. In the presence of serum, TGF-β1 increased outer zone cell proliferation in the micro-wound and in the cross section of meniscal repair model explants. Both IL-1 and TNF-α decreased the integrative shear strength of repair and extracellular matrix deposition in the meniscal repair model system, while TGF-β1 had no effect on either measure.

Conclusions

Meniscal cell proliferation in vivo may be diminished following joint injury due to the up-regulation of inflammatory cytokines, thereby limiting native cellular repair of meniscal lesions. Therefore, therapies that can promote meniscal cell proliferation have promise to enhance meniscal repair and improve tissue engineering strategies.