Paracrine effect of canine allogenic umbilical cord blood-derived mesenchymal stromal cells mixed with beta-tricalcium phosphate on bone regeneration in ectopic implantations.
OBJECTIVE
The aim of this study was to evaluate the paracrine effects of canine umbilical cord blood (cUCB) mesenchymal stromal cells (MSC) mixed with beta-tricalcium phosphate (beta-TCP) on bone regeneration in ectopic implantation.


METHODS
beta-TCP mixed with cUCB MSC (UCB-MSC group), cell lysates (cell lysate group) or a control (control group) were respectively implanted in a subcutaneous pouches in the back of beagle dogs . The implants were harvested 1, 4, 7, 14, 28, 56, 84 days after implantation. Histological findings and stain analyzes of tartrate-resistant acid phosphatase (TRACP) and assays of alkaline phosphatase (ALP) and TRACP were evaluated. The mRNA expression levels of interleukin-1 (IL-1), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), cyclooxygenase-2 (COX-2), vascular endothelial growth factor (VEGF) and transforming growth factor-beta (TGF-beta) were analyzed using semi-quantitative reverse transcription - polymerase chain reactions (RT-PCR). An enzyme-linked immunosorbent assay (ELISA) was used to confirm the protein expression levels of IL-6, COX-2, VEGF and TGF-beta.


RESULTS
TRACP-positive cells were observed in all groups 7 days after implantation. ALP and TRACP activities in the UCB-MSC group 84 days after implantation were significantly higher than those of the control (P>0.05). Histologic findings after 84 days showed that the osteoid matrix area in the UCB-MSC group was significantly larger than that of the control (P<0.05). The mRNAs levels of IL-1, IL-6 and VEGF in UCB-MSC and cell lysate groups on day 1 were up-regulated compared with the control. The protein levels of IL-6 and VEGF in the UCB-MSC group at day 1 were significantly higher than that of the other groups (P<0.05).


CONCLUSIONS
It is suggested that a significant release of cytokines by cUCB MSC, 1 day following implantation, could enhance bone regeneration.
Byeon
Ye-Eun
YE
Department of Veterinary Surgery, College of Veterinary Medicine, Seoul National University, Seoul, Korea.
Ryu
Hak-Hyun
HH
Park
Sung Su
SS
Koyama
Yoshihisa
Y
Kikuchi
Masanori
M
Kim
Wan Hee
WH
Kang
Kyung-Sun
KS
Kweon
Oh-Kyeong
OK
D000135:Acid Phosphatase / Q000378:metabolism; D000818:Animals; D001861:Bone Regeneration; D002130:Calcium Phosphates / Q000378:metabolism; D051546:Cyclooxygenase 2 / Q000096:biosynthesis / Q000235:genetics; D016207:Cytokines / Q000096:biosynthesis* / Q000235:genetics; D062109:Dermatologic Surgical Procedures; D004285:Dogs; D005312:Fetal Blood / Q000166:cytology; D007527:Isoenzymes / Q000378:metabolism; D045164:Mesenchymal Stem Cell Transplantation; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D010012:Osteogenesis; D019899:Paracrine Communication; D012867:Skin / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D000071681:Tartrate-Resistant Acid Phosphatase; D014184:Transplantation, Homologous; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis / Q000235:genetics
D002130:Calcium Phosphates; D016207:Cytokines; D007527:Isoenzymes; D042461:Vascular Endothelial Growth Factor A; C485817:beta-tricalcium phosphate; D051546:Cyclooxygenase 2; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase