Transient activation of AMP-activated protein kinase at G1/S phase transition is required for control of S phase in NIH3T3 cells.

AMP-activated protein kinase (AMPK) functions as a cellular energy sensor by monitoring the cellular AMP:ATP ratio and plays a central role in cellular and whole-body energy homeostasis. Recent studies have suggested that AMPK also contribute to cell cycle regulation, but its role in this field remains almost elusive. In the present study, we report that AMPKα1 was transiently activated during G1/S transition phase in NIH3T3 cells in the absence of any metabolic stress. Inhibition of AMPK activity at G1/S transition phase completely blocked cells from entering S phase; in contrast, persistent activation of AMPK at G1/S transition phase allowed cells to normally enter S phase, but these cells failed to proceed to G2/M phase, stacking at S phase. We further demonstrated that activation of AMPK at G1/S transition phase depends on Ca2+ transients and CaMKKß activity, but not on energy status. Collectively, these data indicate that temporal regulation of AMPK is required for proper control of S phase in NIH3T3 cells.

In-vitro and in-vivo biocompatibility of dECM-alginate as a promising candidate in cell delivery for kidney regeneration.

In this study, kidney decellularized extracellular matrix (dECM) and alginate (ALG) hybrid injectable hydrogel, with the purpose of delivering progenitor cells for tissue engineering, were prepared by using a physical crosslinking method in a CaCl2 solution with high porosity for the exchange of nutrition and waste. In addition, the physical appearance and surface morphology of the hydrogel were investigated using optical and scanning electron microscopy, respectively. The functional groups of the dECM/ALG xerogels was examined via Fourier transform infrared spectroscopy. The biocompatibility of dECM/ALG xerogels was examined in-vitro using renal progenitor cells obtained from adult rat kidney. Enhanced biocompatibility and significant hemostatic behavior was noticed. Furthermore, the in-vivo biocompatibility of dECM/ALG hydrogel with progenitor cells was determined in the deep renal cortex for 7 and 21 days, in order to assess the foreign body reaction and inflammatory response. Early-stage glomerulus-like structure and dense linear cell network-like phenomenon were noticed. Loading of progenitor cells together with hydrogel enhances the cell density obviously due to cell migration from host and form a pattern. The desired early stage in-vivo response to progenitor cell-laden dECM/ALG hydrogel plays a potential role in kidney regeneration long term.

In-vitro and in-vivo hemostat evaluation of decellularized liver extra cellular matrix loaded chitosan/gelatin spongy scaffolds for liver injury.

Individually, Chitosan (C) and Gelatin (G) are increasingly being used for the simulation and testing of surgical procedures. In the present study, at combination of chitosan/gelatin (CG) was optimized and later enriched by the loading decellularized liver extracellular matrix powder (dLECM) prepared from porcine liver, we hypothesized CG-dLECM combination would enhance wound healing and reduce postoperative complications after liver surgery. Varying concentration of dLECM (1, 4, and 8 mg/ml) were loaded into CG, and evaluation was done to get the optimized composition. Preliminary analysis on the microstructure, in-vitro degradation, and blood clot kinetics and in-vitro cytocompatibility showed that the CG with 4 mg/ml dLECM (CG-E4) was the most suitable composition for further consideration. The prepared CG-E4 spongy scaffold enhances fast post-operative recovery with a higher blood absorption and fast clotting time (~50 s). In addition, CG-E4 spongy scaffold implanted at rat liver wound showed desired biocompatibility as evidenced by reduced wound size, earlier bioabsorption and accelerated liver regeneration. In the present study, we demonstrated that, CG with dLECM spongy scaffold as a potential hemostatic material in the prevention of excessive hemorrhage during surgeries.

Physico-mechanical and biological evaluation of an injectable m-TG cross-linked thrombin loaded amended gelatin hemostat to heal liver trauma.

Free flow hemostatic agents are dominating over non-flowable hemostats due to their ability to cover asymmetrical wound surfaces of any depth and easily remove excess materials with irrigation. The objective of this study was to evaluate the activation of a coagulation system both in vitro and in vivo. We assessed detailed physical characteristics of a microbial transglutaminase (m-TG) crosslinked thrombin (TB) laden Gelatin (Gel) hemostat sealant in vitro and its hemostatic efficacy for controlling bleeding caused by liver trauma in rats as well as its efficacy for organ regeneration after making a critical defect. The prepared hemostat gel showed almost seven times higher absorbance behavior than a negative control. Thrombogenicity of the prepared gel was determined based on platelet adhesion, whole blood clotting time, and total blood absorption behavior. In vivo blood absorption and hematological parameters were determined in an animal model after implantation. The prepared gel was able to lead to a fast post-operative recovery with a blood absorption at wound defect. High speed of homeostasis was achieved by a fast clotting time in about 1 min.