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Traditional haemostatic materials generally have slow hemostasis rate and poor biocompatibility. This paper reports on the haemostatic properties and mechanism of silk fibroin (SF). SF-PEG sponge that could be solubilised and changed to gel form by blood was fabricated through mixing SF and polyethylene glycol (PEG, 1500 Da) followed by lyophilisation of the mixed solution. SF-PEG sponge, together with control samples of SF sponge (no PEG) and a commercially available haemostatic material, gelatine sponge, were subjected to the hemostasis tests using a liver trauma model of rabbit. The results showed that SF was superior to gelatine sponge in hemostasis time (136.17 ± 62.27 s and 249.83 ± 29.18 s) and blood loss (2.16 ± 1.27 g vs. 4.97 ± 1.44 g). Furthermore, in vitro experiments indicated SF-PEG sol-gel transition promoted platelet adhesion and aggregation, as well as platelet-fibrinogen interaction. Therefore, except for the physical blocking of bleeding port due to PEG-induced SF fast gelation, SF might also have an impact on blood coagulation process, a phenomenon that has not been reported before. In conclusion, SF is a new type of haemostatic material that might be able to meet the requirements of speed, efficiency and biosafety in a variety of clinical applications. [ABSTRACT FROM AUTHOR]

Senile osteoporosis is closely related to the loss of function of stem cells. In this study, we tried to investigate the potential of secretome from human umbilical cord-derived mesenchymal stem cells (hUCMSCs) in recovering stem cell ability from senescence and then delaying bone loss. We first harvested bone marrow-derived mesenchymal stem cells (BMSCs) from young and old rats and then compared their cellular characteristics such as cell growth, anti-senescence and differentiation. The results showed that these abilities were negatively affected by animal aging. Subsequently, aged BMSCs were exposed to secretome from hUCMSCs, and we found that this loss of cell potential can be modified by secretome treatment. Thereafter, the secretome was loaded into silk fibroin-based hydrogels and used for an in vivo animal study. The results showed that compared to the old untreated group, the bone formation capacity of aged rats was improved by local treatment of secretome-loaded silk fibroin hydrogels. In conclusion, these findings demonstrated that secretome from hUCMSCs has the capacity to recover stem cell potential and delay local bone loss in age-related osteoporosis, which could potentially be applied in osteoporosis therapy in the future. [ABSTRACT FROM AUTHOR]