Potency Assays for Mesenchymal Stromal Cell Secretome-Based Products for Tissue Regeneration

Adult stem cells maintaining tissue homeostasis and regeneration are tightly regulated by their specific microenvironments or stem cell niches. The dysfunction of niche components may alter the activity of stem cells and ultimately lead to intractable chronic or acute disorders. To overcome this dysfunction, niche-targeting regenerative medicine treatments such as gene, cell, and tissue therapy are actively investigated. Here, multipotent mesenchymal stromal cells (MSCs), and particularly their secretomes, are of high interest due to their potency to recover and reactivate damaged or lost stem cell niches. However, a workflow for the development of MSC secretome-based products is not fully covered by regulatory authorities, and and this issue significantly complicates their clinical translation and has possibly been expressed in a huge number of failed clinical trials. One of the most critical issues in this regard relates to the development of potency assays. In this review, guidelines for biologicals and cell therapies are considered to be applied for the development of potency assays for the MSC secretome-based products that aim for tissue regeneration. Specific attention is paid to their possible effects on stem cell niches and to a spermatogonial stem cell niche in particular.

Automated summary

Adult stem cells are regulated by their specific microenvironments called stem cell niches, and dysfunction of the niche components can lead to chronic or acute disorders. To address this, regenerative medicine treatments such as gene and cell therapy are being investigated, with a focus on mesenchymal stromal cells (MSCs) and their secretomes. However, the development of MSC secretome-based products is not fully regulated, which has complicated their clinical translation and resulted in failed trials. This review discusses the development of potency assays for MSC secretome-based products, specifically their effects on stem cell niches and spermatogonial stem cell niche.