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Circulating nucleated peripheral blood cells contribute to early‐phase meniscal healing
Author(s) -
Yamasaki Shinya,
Hashimoto Yusuke,
Takigami Junsei,
Terai Shozaburo,
Takahashi Masafumi,
Wakitani Shigeyuki,
Nakamura Hiroaki
Publication year - 2017
Publication title -
journal of tissue engineering and regenerative medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.835
H-Index - 72
eISSN - 1932-7005
pISSN - 1932-6254
DOI - 10.1002/term.1955
Subject(s) - meniscus , chondrogenesis , confocal , histology , confocal microscopy , green fluorescent protein , chemistry , anatomy , fibrocartilage , pathology , medicine , cartilage , osteoarthritis , biology , microbiology and biotechnology , articular cartilage , biochemistry , physics , geometry , mathematics , alternative medicine , incidence (geometry) , gene , optics
The purpose of this study was to assess how peripheral blood cells (PBCs) contribute to meniscus repair, using a parabiotic rat model. Wild‐type (WT) and green fluorescent protein (GFP) transgenic rats were conjoined at the torso. After 4 weeks, the anterior part of the medial meniscus of both groups of rats was removed. At 1, 2, 4, 8 and 12 weeks post‐meniscectomy, repaired tissue was evaluated using stereomicroscopy, histology with toluidine blue staining, and immunofluorescence microscopy. Stereomicroscopic observations and confocal laser microscopy revealed that a high number of GFP‐positive cells were present in the repaired meniscus of WT rats 1 week post‐meniscectomy, and the number of GFP‐positive cells decreased over time. Based on blood chimerism, the ratios of PBCs in the repaired meniscus were 20.5 ± 2.3% at 1 week, 8.3 ± 0.9% at 2 weeks, 4.4 ± 0.9% at 4 weeks, 2.1 ± 0.9% at 8 weeks, and 0.5 ± 0.4% at 12 weeks, post‐meniscectomy. Histologically, fibrochondrocytes were observed in the repaired meniscus of WT rats after 4 weeks, some of which were GFP‐positive. The chondrogenic marker, type II collagen, was merged within the PBCs in the repaired tissue. However, type‐II‐collagen‐positive cell ratio and metachromasia in the repaired meniscus were not equivalent in normal meniscal tissue. This indicated that PBCs were present within the repaired meniscus at an early phase, replacing the excised meniscal cells, suggesting PBCs contributed to meniscal healing. The tissue repair contribution by these cells decreased at later phases. Copyright © 2014 John Wiley & Sons, Ltd.