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Immunohistochemical localization of mesenchymal stem cells in ossified human spinal ligaments
Shunfu Chin1, Ken-Ichi Furukawa, Atsushi Ono
1Department of Pharmacology, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, Aomori 036-8562, Japan.
Abstract:
Mesenchymal stem cells (MSCs) have been isolated from various tissues and used for elucidating the pathogenesis of numerous diseases. In our previous in vitro study, we showed the existence of MSCs in human spinal ligaments and hypothesized that these MSCs contributed to the pathogenesis of ossification of spinal ligaments. The purpose of this study was to use immunohistochemical techniques to analyze the localization of MSCs in ossified human spinal ligaments in situ. Ossified (OLF) or non-ossified ligamentum flavum (non-OLF) samples from the thoracic vertebra were obtained from patients who had undergone posterior spinal surgery. Serial sections were prepared from paraffin-embedded samples, and double immunofluorescence staining was performed using antibodies against markers for MSCs (CD73, CD90 and CD105), endothelial cells (CD31), pericytes (α-smooth muscle actin), and chondrocytes (S100). Immunolocalization of MSCs was observed in the perivascular area and collagenous matrix in spinal ligaments. Markers for MSCs and pericytes were co-expressed in the perivascular area. Compared with non-OLF, OLF had a large amount of neovascularization in the fragmented ligament matrix, and a high accumulation of MSCs around blood vessels. The prevalence of MSCs in OLF within collagenous matrix was significantly higher than that in non-OLF. Chondrocytes near the ossification front in OLF also presented expression of MSC markers. MSCs may contribute to the ectopic ossification process of OLF through endochondral ossification.
Insights
Mesenchymal stem cells (MSCs) were found in human spinal ligaments, particularly around blood vessels in ossified ligaments. These MSCs may drive ectopic ossification via endochondral ossification.
Area of Science:
- Orthopedics and Regenerative Medicine
- Stem Cell Biology
- Spinal Pathophysiology
Background:
- Mesenchymal stem cells (MSCs) are crucial for tissue repair and disease pathogenesis.
- Previous in vitro studies identified MSCs in human spinal ligaments.
- A hypothesis proposed MSCs contribute to spinal ligament ossification.
Purpose of the Study:
- To investigate the in situ localization of MSCs within ossified human spinal ligaments.
- To determine the relationship between MSCs and neovascularization in ossification of the ligamentum flavum (OLF).
Main Methods:
- Immunohistochemistry and double immunofluorescence staining on thoracic spinal ligament samples (ossified OLF and non-OLF).
- Antibodies used: MSC markers (CD73, CD90, CD105), endothelial cells (CD31), pericytes (α-smooth muscle actin), and chondrocytes (S100).
Main Results:
- MSCs were localized in perivascular areas and the collagenous matrix of spinal ligaments.
- Co-expression of MSC and pericyte markers was observed in the perivascular region.
- Ossified OLF showed increased neovascularization and higher MSC accumulation around blood vessels compared to non-OLF.
- MSCs were significantly more prevalent in the collagenous matrix of OLF.
- Chondrocytes at the ossification front in OLF expressed MSC markers.
Conclusions:
- MSCs are present in human spinal ligaments, particularly in perivascular regions.
- Increased MSCs and neovascularization correlate with ossification of the ligamentum flavum.
- MSCs likely contribute to ectopic ossification of OLF through an endochondral ossification pathway.
