Biodegradable poly(l-lactide)/calcium phosphate composites with improved properties for orthopedics: Effect of filler and polymer crystallinity

Using poly-L-lactic acid for implantable biodegradable scaffold has potential biocompatibility issue due to its acidic degradation byproducts. We have previously reported that the addition of amorphous calcium phosphate improved poly-L-lactic acid coating biocompatibility. In the present study, poly-L-lactic acid and poly-L-lactic acid/amorphous calcium phosphate scaffolds were implanted in pig coronary arteries for 28 days. At the follow-up angiographic evaluation, no case of stent thrombosis was observed, and the arteries that were stented with the copolymer scaffold had significantly less inflammation and nuclear factor-κB expression and a greater degree of reendothelialization. The serum levels of vascular endothelial growth factor and nitric oxide, as well the expression of endothelial nitric oxide synthase and platelet-endothelial cell adhesion molecule-1, were also significantly higher. In conclusion, the addition of amorphous calcium phosphate to biodegradable poly-L-lactic acid scaffold minimizes the inflammatory response, promotes the growth of endothelial cells, and accelerates the reendothelialization of the stented coronary arteries.

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Polymeric Calcium Phosphate Cements Incorporated with Poly-γ-Glutamic Acid

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.396-398.265 ◽

2008 ◽

Vol 396-398 ◽

pp. 265-268

Author(s):

Sung Soo Kim ◽

Sung Jae Lee ◽

Yong Sik Kim ◽

Kwon Yong Lee

Keyword(s):

Citric Acid ◽

Calcium Phosphate ◽

Glutamic Acid ◽

Setting Time ◽

Physiological Saline ◽

Initial Setting Time ◽

Calcium Phosphate Cements ◽

Physiological Saline Solution ◽

Biodegradable Poly ◽

Initial Setting

Polymeric calcium phosphate cements (PCPC) derived from biodegradable poly-g-glutamic acid (g-PGA) were prepared in an attempt to improve the mechanical strength of calcium phosphate cement (CPC). The characteristics of the PCPCs were compared to those of cement incorporated with citric acid. The diametral tensile and compressive strengths of the CPC incorporated with g-PGA were significantly higher than that of cement incorporated with citric acid at equivalent concentrations (p<0.05). The maximal diametral tensile and compressive strengths of the CPC incubated for 1 week in physiological saline solution were approximately 18.0 and 50.0 MPa, respectively. However, the initial setting time of the PCPC was much slower than that of CPC incorporated with citric acid. The formation of ionic complexes between calcium ions and g-PGA was observed using FT-IR spectroscopy. Hydroxyapatite (HA) formation was retarded by g-PGA incorporation according to scanning electronic microscopy (SEM) and powder X-ray diffraction (XRD) observations.

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Nano-Calcium Phosphate/PLLA Incorporated with bFGF as In Situ-Transplantable Carrier for Cartilage Regeneration

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.309-311.953 ◽

2006 ◽

Vol 309-311 ◽

pp. 953-956

Author(s):

Xin Huang ◽

Wei Qi Yan ◽

Di Sheng Yang ◽

Jie Feng ◽

Yan Bo Feng ◽

...

Keyword(s):

Calcium Phosphate ◽

Weight Bearing ◽

Fibrous Tissue ◽

Rabbit Model ◽

Cartilage Regeneration ◽

Cartilage Tissue ◽

Biodegradable Poly ◽

Safranin O

A novel composite of biodegradable Poly-L-lactic acid (PLLA) with the deposition of the nanosized amorphous calcium phosphate (NCP) particles was developed as tissue engineering scaffold. To improve the minor intrinsic healing capacity of cartilage tissue, the porous composite with desired degradation rate was incorporated with basic fibroblast growth factor (bFGF) and evaluated in the in vivo environment. Full-thickness defects were created in the weight-bearing surface of the femoral condyles in a rabbit model. The defect was filled with and without NCP/PLLA scaffold as a carrier of bFGF. Gross morphology for the test implant showed that the defect was filled with regenerated tissue. It resembled cartilaginous tissue and restored the contour of the condyle at 8 weeks after operation. For the untreated control, no cartilage-like tissue was observed at all defects. Histological analysis revealed neochondrogenesis and clusters of cartilaginous extracellular matrix observed with safranin-O staining at 4 weeks for the NCP/PLLA with bFGF treated defects. At 8 weeks after operation, well-formed and mature cartilage was resurfaced the defects. While only fibrous tissue replacement was observed for the control either at 4 or 8 weeks. Special staining for cartilage indicated the presence of highly sulfated glycosaminoglycans and collagen, which were the major extracellular matrices of cartilage. This investigation showed the potential of NCP/PLLA loaded with bFGF in the study of in situ-transplantable carrier to improve healing of cartilage tissue lesion.

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