HOXA13 promotes liver regeneration through regulation of BMP-7

Role of mitogens in normal and pathological liver regeneration

The liver has a unique ability to regenerate to meet the body's metabolic needs, even following acute or chronic injuries. The cellular and molecular mechanisms underlying normal liver regeneration have been well investigated to improve organ transplantation outcomes. Once liver regeneration is impaired, pathological regeneration occurs, and the underlying cellular and molecular mechanisms require further investigations. Nevertheless, a plethora of cytokines and growth factor-mediated pathways have been reported to modulate physiological and pathological liver regeneration. Regenerative mitogens play an essential role in hepatocyte proliferation. Accelerator mitogens in synergism with regenerative ones promote liver regeneration following hepatectomy. Finally, terminator mitogens restore the proliferating status of hepatocytes to a differentiated and quiescent state upon completion of regeneration. Chronic loss of hepatocytes, which can manifest in chronic liver disorders of any etiology, often has undesired structural consequences, including fibrosis, cirrhosis, and liver neoplasia due to the unregulated proliferation of remaining hepatocytes. In fact, any impairment in the physiological function of the terminator mitogens results in the progression of pathological liver regeneration. In the current review, we intend to highlight the updated cellular and molecular mechanisms involved in liver regeneration and discuss the impairments in central regulating mechanisms responsible for pathological liver regeneration.

Mechanisms and translational applications of regeneration in limbs: From renewable animals to humans

BACKGROUND

The regenerative capacity of organisms declines throughout evolution, and mammals lack the ability to regenerate limbs after injury. Past approaches to achieving successful restoration through pharmacological intervention, tissue engineering, and cell therapies have faced significant challenges.

OBJECTIVES

This review aims to provide an overview of the current understanding of the mechanisms behind animal limb regeneration and the successful translation of these mechanisms for human tissue regeneration.

RESULTS

Particular attention was paid to the Mexican axolotl (Ambystoma mexicanum), the only adult tetrapod capable of limb regeneration. We will explore fundamental questions surrounding limb regeneration, such as how amputation initiates regeneration, how the limb knows when to stop and which parts to regenerate, and how these findings can apply to mammalian systems.

CONCLUSIONS

Given the urgent need for regenerative therapies to treat conditions like diabetic foot ulcers and trauma survivors, this review provides valuable insights and ideas for researchers, clinicians, and biomedical engineers seeking to facilitate the regeneration process or elicit full regeneration from partial regeneration events.

Signaling pathways of liver regeneration: Biological mechanisms and implications

The liver possesses a unique regenerative ability to restore its original mass, in this regard, partial hepatectomy (PHx) and partial liver transplantation (PLTx) can be executed smoothly and safely, which has important implications for the treatment of liver disease. Liver regeneration (LR) can be the very complicated procedure that involves multiple cytokines and transcription factors that interact with each other to activate different signaling pathways. Activation of these pathways can drive the LR process, which can be divided into three stages, namely, the initiation, progression, and termination stages. Therefore, it is important to investigate the pathways involved in LR to elucidate the mechanism of LR. This study reviews the latest research on the key signaling pathways in the different stages of LR.

Hepatic vagotomy blunts liver regeneration after hepatectomy by downregulating the expression of interleukin-22

BACKGROUND

Rapid regeneration of the residual liver is one of the key determinants of successful partial hepatectomy (PHx). At present, there is a lack of recognized safe, effective, and stable drugs to promote liver regeneration. It has been reported that vagus nerve signaling is beneficial to liver regeneration, but the potential mechanism at play here is not fully understood.

AIM

To explore the effect and mechanism of hepatic vagus nerve in liver regeneration after PHx.

METHODS

A PHx plus hepatic vagotomy (Hv) mouse model was established. The effect of Hv on liver regeneration after PHx was determined by comparing the liver regeneration levels of the PHx-Hv group and the PHx-sham group mice. In order to further investigate the role of interleukin (IL)-22 in liver regeneration inhibition mediated by Hv, the levels of IL-22 in the PHx-Hv group and the PHx-sham group was measured. The degree of liver injury in the PHx-Hv group and the PHx-sham group mice was detected to determine the role of the hepatic vagus nerve in liver injury after PHx.

RESULTS

Compared to control-group mice, Hv mice showed severe liver injury and weakened liver regeneration after PHx. Further research found that Hv downregulates the production of IL-22 induced by PHx and blocks activation of the signal transducer and activator of transcription 3 (STAT3) pathway then reduces the expression of various mitogenic and anti-apoptotic proteins after PHx. Exogenous IL-22 reverses the inhibition of liver regeneration induced by Hv and alleviates liver injury, while treatment with IL-22 binding protein (an inhibitor of IL-22 signaling) reduce the concentration of IL-22 induced by PHx, inhibits the activation of the STAT3 signaling pathway in the liver after PHx, thereby hindering liver regeneration and aggravating liver injury in PHx-sham mice.

CONCLUSION

Hv attenuates liver regeneration after hepatectomy, and the mechanism may be related to the fact that Hv downregulates the production of IL-22, then blocks activation of the STAT3 pathway.