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Query: UNIPROT:P00750 (PLA)
 16,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of NBM incorporation in PLA nanofibers on their mechanical properties and the differentiation and mineralization of osteoblasts was studied. At 20% NBM, the Young's modulus of the nanofibers was 37.78 +/- 4.23, significantly larger than that of pure PLA nanofibers. MC3T3-E1 pre-osteoblasts attached to both types of nanofibers and developed full osteogenic phenotypes. A profound effect of NBM on the mineralization of MC3T3-E1 pre-osteoblasts was confirmed, suggesting that NBM/PLA composite nanofibers exhibit properties similar to those of the native collagen-rich mineralized bone matrix, and could therefore serve as a temporary substrate for facilitating the differentiation and mineralization of bone-forming cells.
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PMID:Improvement of differentiation and mineralization of pre-osteoblasts on composite nanofibers of poly(lactic acid) and nanosized bovine bone powder. 1878 56

Tissue engineering has become an alternative method to traditional surgical treatments for the repair of bone defects, and an appropriate scaffold supporting bone formation is a key element in this approach. In the present study, nanofibrous organic and inorganic composite scaffolds containing nano-sized demineralized bone powders (DBPs) with biodegradable poly(L-lactide) (PLA) were developed using an electrospinning process for engineering bone. To assess their biocompatibility, in vitro osteogenic differentiation of human mandible-derived mesenchymal stem cells (hMSCs) cultured on PLA or PLA/DBP composite nanofiber scaffolds were examined. The mineralization of hMSCs cultured with osteogenic supplements on the PLA/DBP nanofiber scaffolds was remarkably greater than on the PLA nanofiber scaffold during the first 14 days of culture but reached the same level after 21 days. The in vivo osteoconductive effect of PLA/DBP nanofibrous scaffolds was further investigated using rats with critical-sized skull defects. Micro-computerized tomography revealed that a greater amount of newly formed bone extended across the defect area in PLA/DBP scaffolds than in the nonimplant and PLA scaffolds 12 weeks after implantation and that the defect size was almost 90% smaller. Therefore, PLA/DBP composite nanofiber scaffolds may serve as a favorable matrix for the regeneration of bone tissue.
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PMID:In vitro osteogenic differentiation of human mesenchymal stem cells and in vivo bone formation in composite nanofiber meshes. 1878 80

As a new member of the polyhydroxyalkanoate (PHA) family, poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) (PHBVHHx) was produced by recombinant Aeromonas hydrophila 4AK4. PHBVHHx showed a rougher surface and had higher hydrophobicity than the well-studied polymers poly(L-lactic acid) (PLA) and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx). Human bone marrow mesenchymal stem cells (MSCs) adhered better on PHBVHHx film than on tissue culture plates (TCPs), PLA film and PHBHHx film. The cell number on the PHBVHHx film was 115% higher than that on the TCPs, 66% higher than on the PHBHHx film and 263% higher than on the PLA film (p<0.01). PHBVHHx also supported the osteogenic differentiation of MSCs. Previous studies have shown that all PHA polymers tested were either poorer than or equal to TCPs for supporting cell growth. PHBVHHx is the only PHA polymer to significantly increase cell numbers compared with TCPs. These data demonstrate that PHBVHHx could be a promising biomaterial for bone tissue engineering.
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PMID:Biocompatibility of poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) with bone marrow mesenchymal stem cells. 1897 72

The ideal bone graft material must be biocompatible, biodegradable, osteoconductive and osteoinductive. In this study, a new biomimetic scaffold based on mineralized recombinant collagen, nano-hydroxyapatite/recombinant human-like collagen/poly(lactic acid) (nHA/RHLC/PLA), was prepared and the synthetic P24 peptide derived from BMP-2 was introduced into the porous nHA/RHLC/PLA scaffold to improve its osteoinductive property. The nHA/RHLC/PLA implants loaded with 3 mg, 2 mg, 1 mg and 0 mg P24 peptide were implanted subcutaneously into rats. At the 4th, 8th and 12th weeks after implantation, the rats were sacrificed in batch and the samples were harvested. Their osteogenic capability was detected by CT scan and histological observation. The results indicated that the osteogenic capability of 3 mg, 2 mg and 1 mg of the P24 peptide was superior to the implants without the P24 peptide. There was no significant difference between implants with 3 mg and 2 mg P24 peptide, but the osteogenic capability of the two dosage groups was significantly better than that of the 1 mg group. It was concluded that BMP-2-derived peptide can increase the osteoinduction of nHA/RHLC/PLA scaffold and the P24 peptide induced new bone formation in a dose-dependent manner. The nHA/RHLC/PLA scaffold loaded with the synthetic BMP-2-derived peptide is a kind of ideal scaffold material for bone tissue engineering.
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PMID:Preparation and ectopic osteogenesis in vivo of scaffold based on mineralized recombinant human-like collagen loaded with synthetic BMP-2-derived peptide. 1902 2

Development of tissue-engineered bone constructs has recently focused on the use of electrospun composite scaffolds seeded with stem cells from various source tissues. In this study, we fabricated electrospun composite scaffolds consisting of beta-tricalcium phosphate (TCP) crystals and poly(L-lactic acid) (PLA) at varying loading levels of TCP (0, 5, 10, 20 wt%) and assessed the composite scaffolds' material properties and ability to induce proliferation and osteogenic differentiation of human adipose-derived stem cells (hASCs) in the presence of osteogenic differentiating medium. The electrospun scaffolds all exhibited a nonwoven structure with an interconnected porous network. With the addition of TCP, the fiber diameter increased with each treatment ranging from 503.39 +/- 20.31 nm for 0 wt% TCP to 1267.36 +/- 59.03 nm for 20 wt% TCP. Tensile properties of the composite scaffolds were assessed and the overall tensile strength of the neat scaffold (0 wt% TCP) was 847 +/- 89.43 kPA; the addition of TCP significantly decreased this value to an average of 350.83 +/- 38.57 kPa. As the electrospun composite scaffolds degraded in vitro, TCP was released into the medium with the largest release occurring within the first 6 days. Human ASCs were able to adhere, proliferate and osteogenically differentiate on all scaffold combinations. DNA content increased in a temporal manner for each scaffold over 18 days in culture although for the day 12 timepoint, the 10 wt% TCP scaffold induced the greatest hASC proliferation. Endogenous alkaline phosphatase activity was enhanced on the composite PLA/TCP scaffolds compared to the PLA control particularly by day 18. It was noted that at the highest TCP loading levels of 10 and 20 wt%, there was a dramatic increase in the amount of cell-mediated mineralization compared to the 5 wt% TCP and the neat PLA scaffold. This work suggests that local environment cues provided by the biochemical nature of the scaffold can accelerate the overall osteogenic differentiation of hASCs and encourage rapid ossification.
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PMID:Electrospun composite poly(L-lactic acid)/tricalcium phosphate scaffolds induce proliferation and osteogenic differentiation of human adipose-derived stem cells. 1939 Jan 43

Silicon-releasable microfiber meshes consisting of silicon-doped vaterite (SiV) particles and poly(lactic acid) (PLA) hybrids were prepared by electrospinning. Due to their flexibility and porosity they formed ideal membranes or scaffolds for guided bone regeneration. In addition, a trace amount of silicon species has been reported to stimulate osteogenic cells to mineralize and enhance bone formation. We propose a new method of preparation of silicon-releasing microfiber meshes by electrospinning. Their structure and hydroxyapatite (HA)-forming abilities in simulated body fluid were examined. In addition, we studied their stimulatory effects on osteoblast-like cells in vitro and bone-forming ability in vivo, with a special emphasis on their ability to release silicon. The meshes consisted of a hybrid of carboxy groups in PLA and amino groups in siloxane, derived from aminopropyltriethoxysilane or calcium ions on the SiV surface. This hybrid exhibited an enhanced ability to form HA. The meshes coated with HA released 0.2-0.7 mg l(-1) silicon species into the culture medium over 7 days. Enhanced proliferation of osteoblast-like cells was observed using the meshes and new bone formed on the meshes when implanted into the calvaria of rabbits. These meshes, therefore, provide an excellent substrate for bone regeneration and exhibit enhanced bone-forming ability under both in vitro and in vivo conditions.
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PMID:Electrospun microfiber meshes of silicon-doped vaterite/poly(lactic acid) hybrid for guided bone regeneration. 1991 16

Porous polylactide/beta-tricalcium phosphate (PLA/beta-TCP) composite scaffolds were fabricated by freeze-drying. The aim of this study was to characterize these graded porous composite scaffolds in two different PLA concentrations (2 and 3 wt%). Also, three different beta-TCP ratios (5, 10 and 20 wt%) were used to study the effect of beta-TCP on the properties of the polymer. The characterization was carried out by determining the pH, weight change, component ratios, thermal stability, inherent viscosity and microstructure of the scaffolds in 26 weeks of hydrolysis. This study indicated that no considerable change was noticed in the structure of the scaffolds when the beta-TCP filler was added. Also, the amount of beta-TCP did not affect the pore size or the pore distribution in the scaffolds. We observed that the fabrication method improved the thermal stability of the samples. Our results suggest that, from the structural point of view, these scaffolds could have potential for the treatment of osteochondral defects in tissue engineering applications. The porous bottom surface of the scaffold and the increased osteogenic differentiation potential achieved with beta-TCP particles may encourage the growth of bone cells. In addition, the dense surface skin of the scaffold may inhibit the ingrowth of osteoblasts and bone tissue, while simultaneously encouraging the ingrowth of chondrocytes.
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PMID:Porous polylactide/beta-tricalcium phosphate composite scaffolds for tissue engineering applications. 2008 22

In this study, rabbit adipose-derived stem cells (rASCs) were isolated, cultured in vitro, and transfected with recombinant adenovirus vector containing human bone morphogenetic protein 2 (Ad-hBMP2). These cells were combined with a nano-hydroxyapatite/recombinant human-like collagen/poly(lactic acid) scaffold (nHA/RHLC/PLA) to fabricate a new biocomposite (hBMP2/rASCs-nHA/RHLC/PLA, group 1) and cultured in osteogenic medium. Non-transfected rASCs mixed with nHA/RHLC/PLA (rASCs-nHA/RHLC/PLA, group 2) and nHA/RHLC/PLA scaffold alone (group 3) served as controls. Scanning electron microscope (SEM) demonstrated integration of rASCs with the nHA/RHLC/PLA scaffold. Quantitative real-time RT-PCR analyses of collagen I, osteonectin, and osteopontin cDNA expression indicated that the osteogenic potency of rASCs was enhanced by transfection with Ad-hBMP2. After in vitro culture for seven days, three groups were implanted into 15-mm length critical-sized segmental radial defects in rabbits. After 12 weeks, radiographic and histological analyses were performed. In group 1, the medullary cavity was recanalised, bone was rebuilt and moulding was finished, the bone contour had begun to remodel and scaffold was degraded completely. In contrast, bone defects were not repaired in groups 2 or 3. Furthermore, the scaffold degradation rate in group 1 was significantly higher than in groups 2 or 3. In summary, after transduction with Ad-hBMP2, the osteogenesis of rASCs was enhanced; a new biocomposite created with these cells induced repair of a critical bone defect in vivo in a relatively short time.
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PMID:Enhanced bone formation in large segmental radial defects by combining adipose-derived stem cells expressing bone morphogenetic protein 2 with nHA/RHLC/PLA scaffold. 2014 Jun 71

In order to achieve the sustained release of 3-ethyl-4-(4-methylisoxazol-5-yl)-5-(methylthio) thiophene-2-carboxamide (BFB0261), a new potent osteogenic compound for the treatment of bone disorders, we prepared microspheres containing BFB0261 and newly synthesized three poly (D, L-lactic acid) (PLA), four poly (D, L-lactic acid-co-glycolic acid) (PLGA), and eight poly (D, L-lactic acid)-block-poly(ethylene glycol) (PLA-PEG) biodegradable polymers or copolymers, and evaluated the release pattern of BFB0261 from the microspheres in vitro and in vivo. The mean particle size of the microspheres, except for the microspheres constructed from PLA-PEG with a greater than 20% PEG component, was in the range of approximately 10-50 microm, and the preparations showed a spherical shape with a smooth surface. In an in vitro release study, the release of BFB0261 from PLA-1 (Mw: 36 kDa), PLAPEG9604H (PLA/PEG ratio: 96:4, Mw: 181 kDa), or PLAPEG8317 (PLA/PEG ratio: 83:17, Mw: 106 kDa) microspheres occurred in a zero-order manner with a slow release, and more than 50% of BFB0261 remained in each type of microsphere at 12 weeks after incubation. When the BFB0261 microspheres constructed from various polymers were intramuscularly administered to the rat femur, the microspheres constructed from PLA-1 or PLAPEG9604H were able to achieve a sustained release of BFB0261 at the injection site for 6 weeks. The present information indicates that microspheres constructed from PLA-1 or PLAPEG9604H may be feasible for bone engineering.
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PMID:Preparation and evaluation of biodegradable microspheres containing a new potent osteogenic compound and new synthetic polymers for sustained release. 2022 74

The biochemical factors that regulate cell proliferation and differentiation can provide a means of optimizing culture conditions to develop a tissue-engineered osteochondral construct. Thus, the objectives of this study were to determine the effects of chondrocyte conditioned medium (CM) on the osteogenic differentiation of mesenchymal stem cells (MSCs) cultured on poly(L-lactide-co-epsilon-caprolactone)/hydroxyapatite (PLA/PCL/HAP) scaffolds and to determine the effect of osteoblast CM on the chondrogenic differentiation of MSCs cultured in alginate. In addition, the biomaterial's effect on MSC differentiation was also investigated. MSCs were grown in two groups: (1) on porous PLA/PCL/HAP scaffolds in osteogenic differentiation medium or (2) encapsulated in alginate in chondrogenic differentiation medium. CM was taken from one group and administered to the 'opposite' group in volumetric concentrations of 25% or 50% at each medium change. The osteogenic group samples that were administered chondrocyte CM showed higher alkaline phosphatase activity than the controls that were not administered CM. Additionally, the cells that were given chondrocyte CM had higher osteocalcin and sialoprotein expression than the controls. Samples in the chondrogenic group that were administered osteoblast CM at a volumetric concentration of 50% produced more sGAG than the controls. The aggrecan and Sox9 expression was significantly higher in the samples given 50% CM as compared to the controls. The study also showed that culturing cells in alginate, without differentiation medium, can produce similar levels of differentiation as cells that were administered differentiation medium.
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PMID:Conditioned media enhance osteogenic differentiation on poly(L-lactide-co-epsilon-caprolactone)/hydroxyapatite scaffolds and chondrogenic differentiation in alginate. 2053 95


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