Inhibition of leucine-rich repeats and calponin homology domain containing 1 accelerates microglia-mediated neuroinflammation in a rat traumatic spinal cord injury model.

BACKGROUND: Spinal cord injury (SCI) triggers the primary mechanical injury and secondary inflammation-mediated injury. Neuroinflammation-mediated insult causes secondary and extensive neurological damage after SCI. Microglia play a pivotal role in the initiation and progression of post-SCI neuroinflammation. METHODS: To elucidate the significance of LRCH1 to microglial functions, we applied lentivirus-induced LRCH1 knockdown in primary microglia culture and tested the role of LRCH1 in microglia-mediated inflammatory reaction both in vitro and in a rat SCI model. RESULTS: We found that LRCH1 was downregulated in microglia after traumatic SCI. LRCH1 knockdown increased the production of pro-inflammatory cytokines such as IL-1ß, TNF-α, and IL-6 after in vitro priming with lipopolysaccharide and adenosine triphosphate. Furthermore, LRCH1 knockdown promoted the priming-induced microglial polarization towards the pro-inflammatory inducible nitric oxide synthase (iNOS)-expressing microglia. LRCH1 knockdown also enhanced microglia-mediated N27 neuron death after priming. Further analysis revealed that LRCH1 knockdown increased priming-induced activation of p38 mitogen-activated protein kinase (MAPK) and Erk1/2 signaling, which are crucial to the inflammatory response of microglia. When LRCH1-knockdown microglia were adoptively injected into rat spinal cords, they enhanced post-SCI production of pro-inflammatory cytokines, increased SCI-induced recruitment of leukocytes, aggravated SCI-induced tissue damage and neuronal death, and worsened the locomotor function. CONCLUSION: Our study reveals for the first time that LRCH1 serves as a negative regulator of microglia-mediated neuroinflammation after SCI and provides clues for developing novel therapeutic approaches against SCI.

An efficient method for decellularization of the rat liver.

BACKGROUND/PURPOSE: Using gradient ionic detergent, we optimized the preparation procedure for the decellularized liver biologic scaffold, and analyzed its immunogenicity and biocompatibility. METHODS: EDTA, hypotonic alkaline solution, Triton X-100, and gradient sodium dodecyl sulfate (1%, 0.5%, and 0.1%, respectively) were prepared for continuous perfusion through the hepatic vascular system. The decellularization of the liver tissue was performed with the optimized reagent buffer and washing protocol. In addition, the preservation of the original extracellular matrix was observed. To analyze its biocompatibility, the scaffold was embedded in a heterologous animal and the inflammation features, including the surrounding cell infiltration and changes of the scaffold architecture, were detected. The cell-attachment ability was also validated by the perfusion culture of HepG2 cells with the scaffold. RESULTS: By using gradient ionic detergent, we completed the decellularization process in approximately 5 h, which was shorter than >10 hours in previous experiments (p<0.001). The extracellular matrix was kept relatively intact, with no obvious inflammatory cellular infiltration or structural damage in the grafted tissue. The engraftment efficiencies of HepG2 were 86±5% (n=8). The levels of albumin and urea synthesis were significantly superior to the ones in traditional two-dimensional culture. CONCLUSION: The current new method can be used efficiently for the decellularization of the liver biologic scaffold with satisfying biocomparability for application both in vivo and in vitro.

Current hydrogel solutions for repairing and regeneration of complex tissues.

Hydrogel system, as one of the most important biomaterials, is widely studied because of its tremendous potential in regenerative medicine conferred by its wide range of malleable biochemical and physical characteristics, which include its biocompatibility with the elemental biomolecules in vital tissues, its high water retention capability and adjustable soft-tissue-like physicochemical properties. These properties are modifiable to facilitate the targeted tissue protected from external damaging disturbance and having the encapsulated cells' physiology-functional phenotypes induced or maintained in situ. Recently, hydrogels are increasingly used in the R&D of regenerative medicine to build complex tissue. Most of the insightful work focuses on how to select and fabricate the hydrogel models with desired physicochemical properties, flexibility of auto response to various bio-stimuli, and capability of efficiently forming the complex tissue-mimicking construct at different scales. The present review introduced the major types of hydrogeis, the desirable physicochemical properties, the current fabrication methodologies and special organ-based cases of applications of hydrogels, which are used in complex tissue engineering. In addition, this review also discussed the major hurdles faced by the R&D of hydrogel systems for complex tissue medicine.