Extracellular matrix composition of connective tissues: a systematic review and meta-analysis

Abstract

The function of connective tissues depends on the physical and biochemical properties of their extracellular matrix (ECM), which are in turn dictated by ECM protein composition. With the primary objective of obtaining quantitative estimates for absolute and relative amounts of ECM proteins, we performed a systematic review of papers reporting protein composition of human connective tissues. Articles were included in meta-analysis if they contained absolute or relative quantification of proteins found in the ECM of human bone, adipose tissue, tendon, ligament, cartilage and skeletal muscle. We generated absolute quantitative estimates for collagen in articular cartilage, intervertebral disk (IVD), skeletal muscle, tendon, and adipose tissue. In addition, sulfated glycosaminoglycans were quantified in articular cartilage, tendon and skeletal muscle; total proteoglycans in IVD and articular cartilage, fibronectin in tendon, ligament and articular cartilage, and elastin in tendon and IVD cartilage. We identified significant increases in collagen content in the annulus fibrosus of degenerating IVD and osteoarthritic articular cartilage, and in elastin content in degenerating disc. In contrast, collagen content was decreased in the scoliotic IVD. Finally, we built quantitative whole-tissue component breakdowns. Quantitative estimates improve our understanding of composition of human connective tissues, providing insights into their function in physiology and pathology.

Skeletal Muscle Extracellular Matrix – What Do We Know About Its Composition, Regulation, and Physiological Roles? A Narrative Review

“…The IMCT contains various forms of collagens with types I and III being most abundant (Duance et al, 1977;Light and Champion, 1984;Gillies and Lieber, 2011;McKee et al, 2019). The endomysium interfaces with the myofiber sarcolemma at a specialized basement membrane, which consists primarily of type IV collagen and laminin (Sanes, 1982;Martin and Timpl, 1987;Kjaer, 2004).…”

“…The collagen superfamily contains a total of 28 different members, of which types I, III, IV, V, VI, XII, XIII, XIV, XV, XVIII, and XXII have been shown to be present in mature skeletal muscle at the gene and/or protein level ( Table 1). The fibril-forming types I and III are by far most abundant, with proteomic studies suggesting that they jointly account for approximately 75% of total muscle collagen (McKee et al, 2019). The strong parallel fibers of type I collagen, which are present in the endo-, peri-, and epimysium, are assumed to confer tensile strength and rigidity to the muscle, whereas type III collagen forms a loose meshwork of fibers that bestows elasticity to the endo-and perimysium (Kovanen, 2002).…”

Remodeling the Skeletal Muscle Extracellular Matrix in Older Age—Effects of Acute Exercise Stimuli on Gene Expression

“…COL1A1 is a gene encoding the collagen type I alpha chain, which is a fibril-forming collagen present in all layers of intramuscular connective tissue and the most abundant form of collagen in muscle [ 55 ]. Earlier studies performed by us [ 44 ] and others [ 56 , 57 ] have shown that an acute bout of conventional (i.e., concentric-eccentric) resistance exercise increases either the expression of COL1A1 or collagen protein fractional synthesis rates within 1.0–8.5 h in young muscle.…”

Advanced Bottom‐Up Engineering of Living Architectures

“…Importantly, the observed mechanical improvement was highly dependent on polymers molecular weight, nanoparticles surface chemistry, concentration and size, being mainly observed for particles (<100 nm) . Such indicates that various parameters must be carefully investigated to achieve optimal mechanical properties of printed constructs always taking as reference those of the native tissues one aims to recapitulate …”