Methods and Limitations of Augmenting Mesenchymal Stem Cells for Therapeutic Applications

Abstract

Significance: Given their capacity for self-renewal, multilineage differentiation, and immunomodulatory potential, mesenchymal stem cells (MSCs) represent a promising modality of clinical therapy for both regenerative medicine and immune diseases. In this study, we review the key approaches and popular methods utilized to boost potency and modify functions of MSCs for clinical purposes as well as their associated limitations. Recent Advances: Several major domains of cell modification strategies are currently employed by investigators to overcome these deficits and augment the therapeutic potential of MSCs. Priming MSCs with soluble factors or pharmacologic agents as well as manipulating oxygen availability in culture have been demonstrated to be effective biochemical methods to augment MSC potential. Distinct genetic and epigenetic methods have emerged in recent years to modify the genetic expression of target proteins and factors thereby modulating MSCs capacity for differentiation, migration, and proliferation. Physical methods utilizing three-dimensional culture methods and alternative cell delivery systems and scaffolds can be used to recapitulate the native MSC niche and augment their engraftment and viability for in vivo models. Critical Issues: Unmodified MSCs have demonstrated only modest benefits in many preclinical and clinical studies due to issues with cell engraftment, viability, heterogeneity, and immunocompatibility between donor and recipient. Furthermore, unmodified MSCs can have low inherent therapeutic potential for which intensive research over the past few decades has been dedicated to improving cell functionality and potency.

Keywords: cell-based therapy; mesenchymal stem cell; stem cell therapy.

Omaida C. Velazquez, MD

Zhao Jun-Liu, MD, PhD

Figure 1.

Examples of clinical disease applications for MSC therapy. MSC, mesenchymal stem cell.

Figure 2.

Overview of mesenchymal stem cell properties.

Figure 3.

Schematic of common methods to augment mesenchymal stem cells for therapeutic applications.

Figure 4.

Effects of MSCs modified by differential priming methods.

Figure 5.

Drawbacks of utilizing biochemical methods to prime MSCs.

Figure 6.

Common limitations of genetically modifying MSCs for clinical therapy using viral vectors and genome editing.

Figure 7.

Epigenetic approaches to modify MSCs with their associated limitations.

Figure 8.

Three-dimensional culture methods to produce MSC spheroids in vitro.

Figure 9.

Recognized limitations of MSCs exposed to physical methods of modification.

Figure 10.

Factors for consideration in designing future MSC modification protocols for clinical applications.