Age-Associated Changes in Cartilage Matrix

Abstract

S153The structure of the extracellular matrix of articular cartilage varies considerably with age. These changes are attributable to variations in molecular abundance and structure, and they can affect all the matrix components, but none more so than the proteoglycans. Some of these changes are attributable to variations in synthesis whereas others are attributable to variations in degradation, some of the changes occur during juvenile development whereas others occur throughout life, and some of the changes are beneficial to cartilage function whereas others are detrimental. These variations result in a cartilage that not only changes in its phenotype with age, but also in one whose functional properties are changing continuously throughout life. In a similar manner, the cartilage formed during repair also may show considerable variation in structure and function, depending on whether tissue is being replaced or regenerated and whether mature or immature cells are being used. Because all cartilage is not ceated equal, different repair techniques may not be equally efficacious.The repair of articular cartilage lesions involves the substitution of the old, damaged cartilage by a new, intact tissue. This can be achieved by either replacement via cartilage grafting or regeneration via chondrocyte implantation, and various techniques exist for both approaches. 7,32,51 In either case, it is necessary that the new tissue has and maintains a cartilage phenotype, requiring the absence of blood vessels and nerves, the absence of mineralization, List of Abbreviations Used BMPbone morphogenetic protein COMP cartilage oligomeric protein EGF epidermal growth factor GAG glycosaminoglycan MMP matrix metalloproteinase PRELP proline and arginine-rich end leucine-rich repeat protein GlossaryLP3 ϭ a component of link protein that is derived by proteolytic cleavage in the amino terminal region of the intact molecule. The intact link proteins may possess two or one N-linked oligosaccharides in this amino terminal region and are referred to as LP1 or LP2, respectively. Proteolytic cleavage of either LP1 or LP2 generates the same LP3 component.

Effect of Implantation Accuracy on Ankle Contact Mechanics with a Metallic Focal Resurfacing Implant

“…Biological resurfacing techniques have emerged as a means of restoring the articular surface contour with hyaline (or at least hyaline-like) cartilage [2][3][4][5][6][7][8][9][10][11] . Both clinical and laboratory studies have demonstrated that age is a significant factor in outcomes following these resurfacing procedures 4,12,13 . Resurfacing an articular defect…”

Alterações da cartilagem hialina da cabeça do fêmur de ratos Wistar corredores, em função do envelhecimento

“…Desse modo, a cartilagem depende totalmente da integridade da rede macromolecular que forma a matriz extracelular, sendo o colágeno responsável pela resistência à deformação e os PGs atuando frente as forças de compressão (ROUGHLEY;WHITE, 1980;SCHMIDT et al, 1990).…”

“…A estrutura da matriz extracelular da cartilagem articular varia com a idade (ROUGHLEY, 2001). Mudanças relacionadas com o envelhecimento na composição geral da matriz cartilagínea também resultam em um tecido com menor capacidade para lidar com o estresse mecânico (HULDELMAIER et al, 2001;LOESER, 2000).…”

“…Dependendo da pressão mecânica à qual a cartilagem está submetida, no seu meio ambiente ocorrerão mudanças no comportamento e deformação com a idade , como resposta adaptativa ao estresse mecânico (HUDELMAIER et al, 2001;ROUGHLEY, 2001). …”

“…A estrutura da matriz extracelular da cartilagem articular varia com a idade (PLAAS et al, 1997;ROUGHLEY, 2001). Estas variações podem ocorrer na quantidade e na estrutura molecular e podem afetar todos os componentes da matriz, principalmente os PGs.…”