Escherichia coli-derived recombinant human bone morphogenetic protein-2 combined with bone marrow-derived mesenchymal stromal cells improves bone regeneration in canine segmental ulnar defects.
BACKGROUND
Large bone defects in canines usually require assistance to achieve healing. Implantation of osteoinductive factors can promote bone healing, while transplantation of osteoprogenitor cells can enhance bone regeneration. We hypothesized that implantation of an osteoinductive factor, recombinant human bone morphogenetic protein-2 (rhBMP-2), combined with osteoprogenitor cells, bone marrow-derived mesenchymal stromal cells (BMSCs), would synergistically promote bone healing. In this study, we examined the combined effects of Escherichia coli-derived rhBMP-2 and BMSCs on bone healing after implantation into canine ulnar defects.


RESULTS
Critical-sized osteoperiosteal segmental defects (2.5 cm) were created in the ulnae of healthy female beagle dogs, and implanted with combinations of E. coli-derived rhBMP-2 (560 or 140 μg) and autologous BMSCs (10(7), 10(5), or 0 cells). In the present study,18 forelimbs of nine healthy purpose-bred female beagles were used. All six treatment groups contained three forelimbs, and the animals were euthanized after 12 weeks. The control groups (560 and 140 μg/0 cells) were cited from our previous study to reduce the number of experimental animals. Radiographically, the regenerated bone width was significantly increased in the 560 or 140 μg with 10(7) and 10(5) cells groups compared with the 0 cells groups. By quantitative CT, the bone mineral density was higher in the 560 μg with 10(7) and 10(5) cells groups, while non-uniformity of the bone mineral density was improved in the 560 μg with 10(7) and 10(5) cells groups and 140 μg/10(7) cells group. Mechanically, the maximum loads at failure were significantly higher in the 560 μg with 10(7) and 10(5) cells groups. Histologically, the regenerated bone was well-developed and contained osteocyte-like cells marrow cavities, and vessels. However, the osteoclasts and osteoblasts were hardly observed. The osteocyte-like cell numbers were significantly higher in the 560 μg with 10(7) and 10(5) cells and 140 μg with 10(7) and 10(5) cells groups.


CONCLUSIONS
Implantation of E. coli-derived rhBMP-2 and BMSCs led to significantly enhanced bone formation, with improved bone mineral density and reduced non-uniformity of the regenerated bone. Combined implantation of rhBMP-2 and BMSCs may be useful for promotion of bone healing in critical-sized defects in canines.
Division of Veterinary Surgery, Nippon Veterinary and Life Science University, 1-7-1 Kyonan-cho, Musashino, Tokyo, 180-8602, Japan. takamasa.itoi@hotmail.co.jp.
Takamasa
http://orcid.org/0000-0003-4175-0177
T
Itoi
Division of Veterinary Surgery, Nippon Veterinary and Life Science University, 1-7-1 Kyonan-cho, Musashino, Tokyo, 180-8602, Japan.
Yasuji
Y
Harada
HOYA Technosurgical Corporation, 1-1-110 Tsutsujigaoka, Akishima, Tokyo, 196-0012, Japan.
Hiroyuki
H
Irie
HOYA Technosurgical Corporation, 1-1-110 Tsutsujigaoka, Akishima, Tokyo, 196-0012, Japan.
Michiko
M
Sakamoto
Division of Animal and Clinical Regenerative Medicine, Kurashiki University of Science and Arts, 2640 Nishinoura, Tsurajima-machi, Kurashiki, Okayama, 712-8505, Japan.
Katsutoshi
K
Tamura
Division of Veterinary Surgery, Nippon Veterinary and Life Science University, 1-7-1 Kyonan-cho, Musashino, Tokyo, 180-8602, Japan.
Takuya
T
Yogo
Division of Veterinary Anatomy, Nippon Veterinary and Life Science University, 1-7-1 Kyonan-cho, Musashino, Tokyo, 180-8602, Japan.
Satoshi
S
Soeta
Division of Veterinary Anatomy, Nippon Veterinary and Life Science University, 1-7-1 Kyonan-cho, Musashino, Tokyo, 180-8602, Japan.
Hajime
H
Amasaki
Division of Veterinary Surgery, Nippon Veterinary and Life Science University, 1-7-1 Kyonan-cho, Musashino, Tokyo, 180-8602, Japan.
Yasushi
Y
Hara
Division of Veterinary Surgery, Nippon Veterinary and Life Science University, 1-7-1 Kyonan-cho, Musashino, Tokyo, 180-8602, Japan.
Masahiro
M
Tagawa
D000818:Animals; D001672:Biocompatible Materials / Q000627:therapeutic use; D015519:Bone Density / Q000187:drug effects; D050071:Bone Density Conservation Agents / Q000627:therapeutic use; D001854:Bone Marrow Cells / Q000502:physiology; D019485:Bone Morphogenetic Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D001861:Bone Regeneration; D002130:Calcium Phosphates / Q000627:therapeutic use; D004283:Dog Diseases / Q000628:therapy*; D004285:Dogs; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D005260:Female; D006801:Humans; D020007:Implants, Experimental; D045164:Mesenchymal Stem Cell Transplantation / Q000662:veterinary*; D059630:Mesenchymal Stem Cells / Q000502:physiology; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism*; D014457:Ulna / Q000187:drug effects / Q000293:injuries*
D001672:Biocompatible Materials; D050071:Bone Density Conservation Agents; D019485:Bone Morphogenetic Proteins; D002130:Calcium Phosphates; D011994:Recombinant Proteins
Bone marrow-derived mesenchymal stromal cells; Bone regeneration; Canine; Recombinant human bone morphogenetic protein-2; Ulnar defect