In vivo biocompatibility of new nano-calcium-deficient hydroxyapatite/poly-amino acid complex biomaterials.
OBJECTIVE
To evaluate the compatibility of novel nano-calcium-deficient hydroxyapatite/poly-amino acid (n-CDHA/PAA) complex biomaterials with muscle and bone tissue in an in vivo model.


METHODS
Thirty-two New Zealand white rabbits were used in this study. Biomaterials were surgically implanted into each rabbit in the back erector spinae and in tibia with induced defect. Polyethylene was implanted into rabbits in the control group and n-CDHA/PAA into those of the experimental group. Animals were examined at four different points in time: 2 weeks, 4 weeks, 12 weeks, and 24 weeks after surgery. They were euthanized after embolization. Back erector spinae muscles with the surgical implants were examined after hematoxylin and eosin (HE) staining at these points in time. Tibia bones with the surgical implants were examined by X-ray and scanning electron microscopy (SEM) at these points in time to evaluate the interface of the bone with the implanted biomaterials. Bone tissues were sectioned and subjected to HE, Masson, and toluidine blue staining.


RESULTS
HE staining of back erector spinae muscles at 4 weeks, 12 weeks, and 24 weeks after implantation of either n-CDHA/PAA or polyethylene showed disappearance of inflammation and normal arrangement in the peripheral tissue of implant biomaterials; no abnormal staining was observed. At 2 weeks after implantation, X-ray imaging of bone tissue samples in both experimental and control groups showed that the peripheral tissues of the implanted biomaterials were continuous and lacked bone osteolysis, absorption, necrosis, or osteomyelitis. The connection between implanted biomaterials and bone tissue was tight. The results of HE, Masson, toluidine blue staining and SEM confirmed that the implanted biomaterials were closely connected to the bone defect and that no rejection had taken place. The n-CDHA/PAA biomaterials induced differentiation of a large number of chondrocytes. New bone trabecula began to form at 4 weeks after implanting n-CDHA/PAA biomaterials, and lamellar bone gradually formed at 12 weeks and 24 weeks after implantation. Routine blood and kidney function tests showed no significant changes at 2 weeks and 24 weeks after implantation of both biomaterials.


CONCLUSIONS
n-CDHA/PAA composites showed good compatibility in in vivo model. In this study, n-CDHA/PAA were found to be safe, nontoxic, and biologically active in bone repair.
College of Physical Science and Technology, Sichuan University, Chengdu, People's Republic of China ; Department of Orthopedics, Chongqing Hospital of Traditional Chinese Medicine, Chongqing Medical University, Chongqing, People's Republic of China.
Zhenyu
Z
Dai
Department of Clinical Laboratory, the Second Affiliated Hospital, Chongqing Medical University, Chongqing, People's Republic of China.
Yue
Y
Li
Department of Orthopedics, Chongqing Hospital of Traditional Chinese Medicine, Chongqing Medical University, Chongqing, People's Republic of China.
Weizhong
W
Lu
Department of Orthopedics, the First Affiliated Hospital, Chongqing Medical University, Chongqing, People's Republic of China.
Dianming
D
Jiang
College of Physical Science and Technology, Sichuan University, Chengdu, People's Republic of China.
Hong
H
Li
College of Physical Science and Technology, Sichuan University, Chengdu, People's Republic of China.
Yonggang
Y
Yan
College of Physical Science and Technology, Sichuan University, Chengdu, People's Republic of China.
Guoyu
G
Lv
College of Physical Science and Technology, Sichuan University, Chengdu, People's Republic of China.
Aiping
A
Yang
D000596:Amino Acids / Q000737:chemistry*; D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry* / Q000494:pharmacology*; D002118:Calcium / Q000737:chemistry; D002454:Cell Differentiation / Q000187:drug effects; D019902:Chondrocytes / Q000187:drug effects / Q000648:ultrastructure; D017886:Durapatite / Q000737:chemistry*; D008297:Male; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D009132:Muscles / Q000166:cytology / Q000187:drug effects; D049329:Nanostructures / Q000737:chemistry*; D011095:Polyethylenes / Q000737:chemistry; D058105:Polymerization; D019736:Prostheses and Implants; D011817:Rabbits; D013977:Tibia / Q000166:cytology / Q000187:drug effects
D000596:Amino Acids; D001672:Biocompatible Materials; D011095:Polyethylenes; D017886:Durapatite; D002118:Calcium
bioactive composite; histological evaluation; in vivo implantation; n-CDHA/PAA