ABSTRACT
The effect of platelet-rich plasma on nerve regeneration remains controversial. In this study, we established a rabbit model of sciatic nerve small-gap defects with preserved epineurium and then filled the gaps with platelet-rich plasma. Twenty-eight rabbits were divided into the following groups (7 rabbits/group): model, low-concentration PRP (2.5-3.5-fold concentration of whole blood platelets), medium-concentration PRP (4.5-6.5-fold concentration of whole blood platelets), and high-concentration PRP (7.5-8.5-fold concentration of whole blood platelets). Electrophysiological and histomorphometrical assessments and proteomics analysis were used to evaluate regeneration of the sciatic nerve. Our results showed that platelet-rich plasma containing 4.5-6.5- and 7.5-8.5-fold concentrations of whole blood platelets promoted repair of sciatic nerve injury. Proteomics analysis was performed to investigate the possible mechanism by which platelet-rich plasma promoted nerve regeneration. Proteomics analysis showed that after sciatic nerve injury, platelet-rich plasma increased the expression of integrin subunit ß-8 (ITGB8), which participates in angiogenesis, and differentially expressed proteins were mainly enriched in focal adhesion pathways. Additionally, two key proteins, ribosomal protein S27a (RSP27a) and ubiquilin 1 (UBQLN1), which were selected after protein-protein interaction analysis, are involved in the regulation of ubiquitin levels in vivo. These data suggest that platelet-rich plasma promotes peripheral nerve regeneration after sciatic nerve injury by affecting angiogenesis and intracellular ubiquitin levels.
ABSTRACT
BACKGROUND: Tissue inhibitor of metalloproteinases (TIMPs) can restrain the tumor growth by their protein property and matrix metalloproteinases (MMPs) inhibition. There are currently four known TIMP family members-TIMP-1, 2, 3, 4. We determined whether increasing levels of TIMP-3 expression could suppress the malignant phenotype of human hepatocarcinoma cell line HCC-7721. METHODS: A recombinant expression vector, which contained full-length cDNA of human TIMP-3, was constructed and transfected into the human hepatocarcinoma cell line HCC-7721 by the lipofectamine technique. In vitro and in vivo tests such as Western blotting, immunohistochemistry as well as xenografting in nude mice were used to analyze expression levels of TIMP and MMP, and changes in malignant phenotype after the gene transfection. RESULTS: TIMP-3 expression in TIMP-3 gene-transfected HCC-7721 cells was upregulated as assessed by Western blotting. The ability of in vitro invasion through a Boyden chamber was significantly decreased compared to controls. Following subcutaneous injection into nude mice, the TIMP-3 transfected cells suppressed primary tumor growth, as characterized by reduced tumor weight, size and microvasculature as well as maintaining the extracellular matrix. CONCLUSION: The results suggest that upregulation of TIMP-3 expression in HCC-7721 cells inhibits invasion capacity in vitro as well as tumorigenic and metastatic potential in nude mice.
