Limited Potential or Unfavorable Manipulations? Strategies Toward Efficient Mesenchymal Stem/Stromal Cell Applications

Abstract

Despite almost 50 years of research and over 20 years of preclinical and clinical studies, the question of curative potential of mesenchymal stem/stromal cells (MSCs) is still widely discussed in the scientific community. Non-reproducible treatment outcomes or even absence of treatment effects in comparison to control groups challenges the potential of these cells for routine application both in tissue engineering and in regenerative medicine. One of the reasons of such outcomes is non-standardized and often disadvantageous ex vivo manipulation of MSCs prior therapy. In most cases, clinically relevant cell numbers for MSC-based therapies can be only obtained by in vitro expansion of isolated cells. In this mini review, we will discuss point by point possible pitfalls in the production of human MSCs for cell therapies, without consideration of material-based applications. Starting with cell source, choice of donor and recipient, as well as isolation methods, we will then discuss existing expansion protocols (two-/three-dimensional cultivation, basal medium, medium supplements, static/dynamic conditions, and hypoxic/normoxic conditions) and influence of these strategies on the cell functionality after implantation. The role of potency assays will also be addressed. The final aim of this mini review is to illustrate the heterogeneity of current strategies for gaining MSCs for clinical applications with their strengths and weaknesses. Only a careful consideration and standardization of all pretreatment processes/methods for the different applications of MSCs will ensure robust and reproducible performance of these cell populations in the different experimental and clinical settings.

Viability, Yield and Expansion Capability of Feline MSCs Obtained from Subcutaneous and Reproductive Organ Adipose Depots

“…MSCs are becoming increasingly relevant to clinical care [7] but the outcomes associated with MSC treatment have shown great inconsistency. Some of the outcome variability may be due to the altered characteristics associated with the cells, based on the site of isolation of the initial tissue [13,27]. Other factors responsible for inducing variability may include the methods of isolation, the amount of tissue harvested, and the passage number.…”

“…MSCs can be harvested from a variety of tissues including adipose tissue, bone marrow, peripheral blood, and umbilical cord [11,12]. Cells from diverse sites have unique properties including basic transcriptome differences and variations in in vitro or in vivo differentiation [13].…”

Innovative approaches for induction of gastrointestinal anastomotic healing: an update on experimental and clinical aspects

“…Those enzymes have the capacity to degrade collagen and thereby endanger the stability of the early anastomotic closure. It has been shown that immediately after surgery the MMP activity is markedly upregulated [8]. In some early animal studies in rats, unselective MMP inhibition could improve bursting pressures [23].…”

“…Several molecular classes as growth factors, interleukins, and chemokines mediate communication between immune cells and matrix forming cells. Collagen degrading enzymes, so-called matrix metalloproteinases (MMP), are key players highly active in the early healing phases [8]. Their balanced regulation is important to allow reorganization of collagen without endangering the integrity of the newly formed collagen layer.…”

Comparative Analysis of Mesenchymal Stem Cell Cultivation in Fetal Calf Serum, Human Serum, and Platelet Lysate in 2D and 3D Systems

“…From that point on, numerous studies about the handling of these cells have been performed. However, the development of an optimal protocol for cultivating MSCs is still in progress (Spees et al, 2016 ; Lavrentieva et al, 2020 ). The most common and most widely used cell culture medium supplement is fetal calf serum (FCS).…”