Behavior of Mesenchymal Stem Cells in the Chemical Microenvironment of the Intervertebral Disc

Abstract

Study Design Responses of mesenchymal stem cells (MSCs) from 2 age groups was analyzed under chemical conditions representative of the intervertebral disc (IVD) (low glucose levels, acidic pH, high osmolarity, and combined conditions). Objective To determine the microenvironmental conditions of the IVD that are critical for MSC-based tissue repair and to determine whether MSCs from different age groups respond differently. Summary of Background Data MSCs offer promise for IVD repair, but their potential is limited by the harsh chemical microenvironment in which they must survive. Methods MSCs were isolated from bone marrow from mature (4–5 month old) and young (1 month old) rats and cultured in monolayer under IVD-like glucose, osmolarity, and pH conditions as well as under a combination of these conditions and under standard media conditions for 2 weeks. The response of MSCs was examined by measuring gene expression (real-time RT-PCR), proliferation (MTT assay), and viability (fluorescence staining). Results Culturing under IVD-like glucose conditions (1.0 mg/mL glucose) stimulated aggrecan and collagen-1 expression and caused a small increase in proliferation. In contrast, IVD-like osmolarity (485 mOsm) and pH (pH = 6.8) conditions strongly decreased proliferation and expression of matrix proteins, with more pronounced effects for osmolarity. Combining these 3 conditions also resulted in decreased proliferation, and gene expression of matrix proteins, demonstrating that osmolarity and pH dominated the effects of glucose. Both age groups showed a similar response pattern to the disc microenvironment. Conclusion IVD repair using MSCs requires increased knowledge of MSC response to the chemical microenvironment. IVD-like low glucose enhanced matrix biosynthesis and maintained cell proliferation whereas IVD-like high osmolarity and low pH conditions were critical factors that reduced biosynthesis and proliferation of young and mature MSCs. Since osmolarity decreases and acidity increases during degeneration, we speculate that pH may be the major limitation for MSC-based IVD repair.

The effects of dynamic loading on the intervertebral disc

“…Nevertheless, low oxygen tension and hydrostatic pressure alone without TGF-b could not initiate chondrogenesis of MSC [105]. A low glucose condition stimulates anabolic gene expression of MSCs [128]. An acidic environment and high osmolarity, as in the IVD, decrease MSC proliferation and viability, alter MSC morphology and inhibit anabolic gene expression [126,128].…”

“…A low glucose condition stimulates anabolic gene expression of MSCs [128]. An acidic environment and high osmolarity, as in the IVD, decrease MSC proliferation and viability, alter MSC morphology and inhibit anabolic gene expression [126,128]. Overall, the disc environment certainly contains not only factors that favour MSC differentiation towards matrix producing cells but also factors that may hinder MSC survival.…”

Comparison of biological characteristics of nucleus pulposus mesenchymal stem cells derived from non-degenerative and degenerative human nucleus pulposus

“…Numerous stem cell types have been used in the field of cell transplantation for the treatment of IDD, such as bone marrow-derived stem cells (BMSCs) (10), adipose-derived MSCs (ADMSCs) (11), human umbilical tissue-derived cells (12) and synovium-derived stem cells (13 (14,15). Certain studies have reported that these stem cells lack viability, proliferation and matrix biosynthesis under conditions resembling the IVD microenvironment, which negatively influences the biological and metabolic vitality of stem cells and impairs their repair potential (16,17). In recent years, increasing evidence supported the existence of nucleus pulposus MSCs (NPMSCs) in the nucleus pulposus (18)(19)(20)(21)(22)(23)(24).…”

Potential application of notochordal cells for intervertebral disc regeneration: an in vitro assessment

“…Cells are then out of their native tissue which can provide cues, through cell-matrix interactions, that may alter cells' response to www.ecmjournal.org E Potier et al Notochordal cells for IVD regeneration stimulation. The culture system did not include the disc environmental factors, such as low pH or high osmolarity, showed to affect cell behaviour, especially that of BMSCs (Wuertz et al, 2008). Another limitation may be the use of a cross-species model.…”