Construction of wound repair model and function of recombinant TIMP from Hyriopsis cumingii

Metalloproteinase tissue inhibitors (TIMPs) have the activity of inhibiting matrix metalloproteinases (MMPs), which can promote cell growth, bind to the matrix, inhibit angiogenesis, and play a key role in extracellular matrix (ECM) metabolism regulation. In this study, TIMP-1, 2 from Hyriopsis cumingii (designated as HcTIMP-1, 2) were cloned and identified. Full-length cDNA of HcTIMP-1, 2 was 1160 bp and 729 bp, encoding 235 and 150 amino acid residues, respectively. The predicted molecular weight of HcTIMP-1 and 2 protein was 27.26 and 16.58 kDa, with isoelectric points of 8.89 and 8.72, respectively. HcTIMP-2 contained only one netrin (NTR) domain at the N-terminal but lacked a C-terminal domain. The mRNA of HcTIMP-1, 2 was expressed in hepatopancreas, gills, muscles, hemocytes, and mantles, which had the highest expression in hemocytes and muscles. The expression of HcTIMP-1, 2 had increased remarkably in hemocytes after bacterial challenge. After trauma, HcTIMP-1, 2 genes had the highest expression level in the first day. This indicated that HcTIMP-1 and 2 were involved in the immune response of H. cumingii. The soluble recombinant proteins HcTIMP-1, 2 were expressed efficiently in Escherichia coli BL21 (DE3) by constructing pET32a-TIMP1, 2 recombinant plasmids. The concentration of the recombinant was 0.14 and 0.31 mg/mL, respectively. The recombinant HcTIMP-1, 2 proteins were shown to inhibit human MMP2 activity and promoted the growth of NBL-7 and HUVE cells.

Polymer fiber-based models of connective tissue repair and healing

Physiologically relevant models of wound healing are essential for understanding the biology of connective tissue repair and healing. They can also be used to identify key cellular processes and matrix characteristics critical for the design of soft tissue grafts. Modeling the various stages of repair post tendon injury, polymer meshes of varying fiber diameter (nano-1 (390 nm) < nano-2 (740 nm) < micro (1420 nm)) were produced. Alignment was also introduced in the nano-2 group to model matrix undergoing biological healing rather than scar formation. The response of human tendon fibroblasts on these model substrates were evaluated over time as a function of fiber diameter and alignment. It was observed that the repair models of unaligned nanoscale fibers enhanced cell growth and collagen synthesis, while these outcomes were significantly reduced in the mature repair model consisting of unaligned micron-sized fibers. Organization of paxillin and actin on unaligned meshes was enhanced on micro- compared to nano-sized fibers, while the expression and activity of RhoA and Rac1 were greater on nanofibers. In contrast, aligned nanofibers promoted early cell organization, while reducing excessive cell growth and collagen production in the long term. These results show that the early-stage repair model of unaligned nanoscale fibers elicits a response characteristic of the proliferative phase of wound repair, while the more mature model consisting of unaligned micron-sized fibers is more representative of the remodeling phase by supporting cell organization while suppressing growth and biosynthesis. Interestingly, introduction of fiber alignment in the nanofiber model alters fibroblast response from repair to healing, implicating matrix alignment as a critical design factor for circumventing scar formation and promoting biological healing of soft tissue injuries.