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Laser therapy, recently renamed as photobiomodulation, stands as a promising supportive treatment for oral mucositis induced by oncological therapies. However, its mechanisms of action and, more importantly, its safety in cancer patients, are still unclear. Here we explored the anti-cancer effect of 3 laser protocols, set at the most commonly used wavelengths, in B16F10 melanoma and oral carcinogenesis mouse models. While laser light increased cell metabolism in cultured cells, the in vivo outcome was reduced tumor progression. This striking, unexpected result, was paralleled by the recruitment of immune cells, in particular T lymphocytes and dendritic cells, which secreted type I interferons. Laser light also reduced the number of highly angiogenic macrophages within the tumor mass and promoted vessel normalization, an emerging strategy to control tumor progression. Collectively, these results set photobiomodulation as a safety procedure in oncological patients and open the way to its innovative use for cancer therapy., Highlights • Laser light reduces tumor progression while increasing metabolism of cultured cells • Laser-treated tumors contain mature vessels and less pro-angiogenic macrophages • Tumors treated by photobiomodulation are surrounded by lymphocytes and dendritic cells • Laser light promotes secretion of type I interferons in vitro and in vivo Laser therapy, also named photobiomodulation, is recommended to heal mucositis induced by oncological treatments, raising concerns on its safe use in cancer patients. Ottaviani et al. showed that laser light inhibits tumor progression, induces tumor vessel normalization and stimulates the immune system to produce type I interferons, proving the safety and extending the use of laser-based therapies to cancer.

Summary Over the last several years, mesenchymal stromal cells (MSCs) have been isolated from different tissues following a variety of different procedures. Here, we comparatively assess the ex vivo and in vivo properties of MSCs isolated from either adipose tissue or bone marrow by different purification protocols. After MSC transplantation into a mouse model of hindlimb ischemia, clinical and histological analysis revealed that bone marrow MSCs purified on adhesive substrates exerted the best therapeutic activity, preserving tissue viability and promoting formation of new arterioles without directly transdifferentiating into vascular cells. In keeping with these observations, these cells abundantly expressed cytokines involved in vessel maturation and cell retention. These findings indicate that the choice of MSC source and purification protocol is critical in determining the therapeutic potential of these cells and warrant the standardization of an optimal MSC isolation procedure in order to select the best conditions to move forward to more effective clinical experimentation., Graphical Abstract, Highlights • MSCs were isolated from various tissues according to different protocols • All MSCs provided a therapeutic benefit in a hindlimb ischemia model • Adhesive MSCs from bone marrow were the most effective in preserving tissue viability • These cells promoted massive vascularization in a paracrine fashion, Zacchigna and colleagues compared the ex vivo and in vivo properties of mesenchymal stromal cells (MSCs) isolated from either adipose tissue or bone marrow by different protocols. Adhesive MSCs from bone marrow exerted the best therapeutic activity in a hindlimb ischemia model, preserving viability and inducing angiogenesis in a paracrine manner. The optimization of a standard MSC isolation procedure is required to improve clinical results.