20 January 2014

Stem cells give their mitochondria to sick neighbors

Recently, scientists have been receiving more and more data in favor of the fact that stem cells can promote rejuvenation and repair of damaged cells by transferring their mitochondria to them. To do this, the plasma membrane of the donor cell is stretched, forming tubes connecting its cytoplasm with the cytoplasm of the recipient cell. The number of such structures that allow stem cells to share mitochondria with their neighbors increases under stress.

Earlier studies have shown that impaired functioning of the mitochondria of the cells of the pulmonary epithelium is a key link in the pathogenesis of asthma. Researchers from the Institute of Genomics and Integrative Biology (Delhi, India), working under the guidance of Professor Anurag Agrawal, demonstrated that mitochondrial transfer carried out by mesenchymal stem cells promotes the restoration of the pulmonary epithelium in a mouse model of allergic inflammation of the respiratory tract. Moreover, they identified a protein that regulates the movement of mitochondria from cell to cell.

It turned out that mitochondrial transfer is impossible without the Miro1 protein, which is the mitochondrial GTPASE enzyme. Overexpression of this protein by mesenchymal stem cells increases the efficiency of mitochondrial transfer, whereas its absence suppresses the movement of these organelles.

Therapy with mesenchymal stem cells with high expression of Miro1 protein (MSCmiroHi) ensured the disappearance of symptoms of respiratory hyperreactivity in three independent mouse models of allergen-induced asthma. At the same time, the introduction of MSCmiroHi into the culture of human bronchial epithelial cells normalized the functioning of the mitochondria of cells, disrupted as a result of preliminary exposure to the environment containing pro-inflammatory factors in which induced macrophages were cultured. Hyperexpression of Miro1 did not affect the synthesis of compounds with anti-inflammatory properties by mesenchymal stem cells, such as nitric oxide, transforming growth factor beta, interleukin-10 and prostaglandin E2, which excluded non-specific paracrine effects (the term "paracrine" is used to describe hormones that are secreted by endocrine glands and affect the function of those located near them cells; these hormones are practically not carried by blood or lymph at considerable distances from the place of their secretion).

Diagram from the EMBO article

The authors hope to develop approaches that will allow them to use their discovery to increase the effectiveness of cell therapy for human diseases.

Article by Tanveer Ahmad et al. Miro1 regulates intercellular mitochondrial transport & enhances mesenchymal stem cell rescue efficiency published in The EMBO Journal.

Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on EMBO materials:
Stem cells overcome damage in other cells by exporting mitochondria.


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