Proteomic differences between native and tissue‐engineered tendon and ligament

Abstract

Tendons and ligaments (T/Ls) play key roles in the musculoskeletal system, but they are susceptible to traumatic or age‐related rupture, leading to severe morbidity as well as increased susceptibility to degenerative joint diseases such as osteoarthritis. Tissue engineering represents an attractive therapeutic approach to treating T/L injury but it is hampered by our poor understanding of the defining characteristics of the two tissues. The present study aimed to determine differences in the proteomic profile between native T/Ls and tissue engineered (TE) T/L constructs. The canine long digital extensor tendon and anterior cruciate ligament were analyzed along with 3D TE fibrin‐based constructs created from their cells. Native tendon and ligament differed in their content of key structural proteins, with the ligament being more abundant in fibrocartilaginous proteins. 3D T/L TE constructs contained less extracellular matrix (ECM) proteins and had a greater proportion of cellular‐associated proteins than native tissue, corresponding to their low collagen and high DNA content. Constructs were able to recapitulate native T/L tissue characteristics particularly with regard to ECM proteins. However, 3D T/L TE constructs had similar ECM and cellular protein compositions indicating that cell source may not be an important factor for T/L tissue engineering.

Variations in internal structure, composition and protein distribution between intra‐ and extra‐articular knee ligaments and tendons

“…), canine (Kharaz et al. ) and human (Little et al. ) T/Ls, where altered proportions of molecular components, different collagen organisational structures and protein abundance of some ECM proteins have been demonstrated between the two tissue types.…”

Extracellular Matrix Expression and Production in Fibroblast-Collagen Gels: Towards an In Vitro Model for Ligament Wound Healing

“…Kharaz et al reported that decorin is present in fibroblast-collagen gels, albeit in less abundance than native tissue. 28 We also detected decorin production in all gels, with a sharp increase in decorin proteins at two-weeks in stress-free gels. TnC has previously been seen to be stimulated and produced in much higher levels in biaxial stressed gels with chick embryo fibroblasts when compared to the stress-free gels.…”

“…Previous proteomic research determined that collagen type I and collagen type III is abundant and highly expressed in fibroblast hydrogel constructs, but not at the same high level as native ligament tissue. 26,28 Whereas primary human tenocytes cultured in fibrinogen-PGLA scaffolds for 4 weeks expressed genes for collagen type I and collagen type III at levels comparable to native tendon. 45 Our results build upon these findings by showing that the abundance and expression of collagen type I in fibroblast collagen gels is unaffected by culture time when subjected to uniaxial stress and biaxial stress (Fig.…”

“…7, 8), and only the stress-free condition had steady, yet insignificant, increases in collagen type I gene expression with time. Prior studies found that collagen type III is more highly expressed in ligament versus tendon 28 and collagen type III protein content was increased in fibrin-based constructs seeded with primary fibroblasts from canine tendon and ligament that were stimulated with TGF-β1. 21 In the current study, collagen type III expression and production was time dependent, with the greatest protein production under biaxial stress (Fig.…”

“…8,38 Fibroblast migration to the wound site may be helped by increased levels of both tenascin-C 13 and integrin α5 proteins. 42 Although prior studies have evaluated the expression and production of some of these biomarkers in three-dimensional cellular gels, 24,28,37 a comprehensive targeted analysis of these ligament wound healing biomarkers in cellular gels has not yet been conducted.…”