Mesenchymal Stem Cells in Tissue Growth and Repair

Abstract

It has been established in the recent several decades that stem cells play a crucial role in tissue renewal and regeneration. Mesenchymal stem cells (MSCs) are part of the most important population of adult stem cells. These cells have hereby been identified for the very first time and subsequently isolated from bone marrow stroma. Bone marrow-derived MSCs have been believed to play the role of a source of cells for the renewal and repair of connective tissues, including bone, cartilage and adipose tissues. Cells similar to bone marrow-derived MSCs have now been identified in all postnatal tissues. Data on the distribution and function of MSCsin vivocollected using novel approaches pertaining to the identification of MSCsin situ, to their isolation from tissues, and finally to the determination of their biological properties have enabled successful revision of the role of MSCs in various organs and tissues. This review summarizes our own, as well as others’, data concerning the role of MSCs in the regulation processes of tissue repair and regeneration. In our opinion, MSCs provide the connection between the blood-vascular, immune, endocrine, and nervous systems and tissue-specific stem cells in the body.

Activation, homing, and role of the mesenchymal stem cells in the inflammatory environment

“…In recent years, MSCs have been recognized as one of the adult stem cell types, which actively participate in a tissue damage repair processes 50,51. In a case of tissue damage, the MSCs located in immediate vicinity or originated from bone marrow begin to migrate to the site of injury 28,29.…”

“…In a case of tissue damage, the MSCs located in immediate vicinity or originated from bone marrow begin to migrate to the site of injury 28,29. Once the MSCs reach an injury site, they must cooperate closely with various types of stromal and inflammatory cells in order to participate in damage repair and regeneration processes 51,56. It has been shown that there are mutual interactions between the MSCs and inflammatory cells, which at the end determine the results of damaged tissue repair processes mediated by MSCs.…”

“…MSCs can mediate their immunomodulatory activity in a numerous models, such as graft versus host disease (GvHD),34,44 diabetes mellitus type 1,45,46 experimental autoimmune encephalomyelitis (EAE),47 model of contusive spinal cord injury and its subsequent inflammation-related damage,48,49 and many others 33. They may also act as primary matrices in the tissue repair processes caused by the inflammation and injury 50,51. Because of high affinity to the tumor tissue, MSCs can also serve as the targeted carriers of therapeutic agents, as part of the tumor stroma in anticancer therapy 52,53…”

Targeting TGFβ signaling in subchondral bone and articular cartilage homeostasis

“…Adult tissues often harbor resident stem cells or progenitor cells for tissue homeostasis 43 . TGFβs, in consultation with the other signals, appear to regulate stem cells’ decision in differentiation or self-renew.…”

“…MSCs serve to replenish the differentiated compartment of various cell types for bone formation, angiogenesis, adipogenesis and chondrogenesis 61–62, 43, 63–65 . Extrinsic signals in the surrounding microenvironment that are transmitted to the stem cell niche substantially influence MSC self-renewal or differentiation.…”