Porous calcium polyphosphate scaffolds for bone substitute applications in vivo studies

Grynpas, Marc D.; Pilliar, Robert M.; Kandel, Rita A.; Renlund, Richard; Filiaggi, Mark; Dumitriu, M

doi:10.1016/s0142-9612(01)00336-2

Cited by 173 publications

(133 citation statements)

References 10 publications

Supporting

Mentioning

124

Contrasting

Unclassified

Order By: Relevance

“…Calcium phosphate based materials, in particular, have been widely investigated for use as bone replacement materials due to their biocompatibility and osteoconductivity [32,35,[42][43][44]. Synthetic hydroxyapatite (HAP) and β-tricalcium phosphate (β-TCP) are the two most common calcium phosphate materials used as hard-tissue replacements [7].…”

Section: Ceramicsmentioning

confidence: 99%

Osteoblast response to zirconia‐hybridized pyrophosphate‐stabilized amorphous calcium phosphate

Whited

Škrtić

Love

et al. 2005

J Biomedical Materials Res

View full text Add to dashboard Cite

(Abstract)Biodegradable polyesters, such as poly(DL-lactic-co-glycolic acid) (PLGA), have been used to fabricate porous bone scaffolds to support bone tissue development. These scaffolds allow for cell seeding, attachment, growth and extracellular matrix production in vitro and are replaced by new bone tissue when implanted into bone sites in vivo.Hydroxyapatite (HAP) and β-tricalcium phosphate (β-TCP) ceramics have been incorporated into PLGA bone scaffolds and have been shown to increase their osteoconductivity (support cell attachment). Although HAP, β-TCP, and biodegradable polyesters are osteoconductive, there is no evidence that these scaffold materials are osteoinductive (support cell differentiation). Calcium and phosphate ions, in contrast, have been postulated to be osteogenic factors that enhance osteoblast differentiation and mineralization. Recently, a zirconia-hybridized pyrophosphate stabilized amorphous calcium phosphate (Zr-ACP) has been synthesized which permits controlled release of calcium and phosphate ions and thus is hypothesized to be osteoinductive. Incorporation of Zr-ACP into a highly porous poly(DL lactic-co-glycolic acid) (PLGA) scaffold could potentially increase the osteoinductivity of the scaffold and therefore promote osteogenesis when implanted in vivo.To determine the osteoinductivity of Zr-ACP, a MC3T3-E1 mouse calvarialderived osteoprogenitor cell line was used to measure cell response to Zr-ACP. To accomplish this objective, Zr-ACP was added to cell culture at different stages in cell maturation (days 0, 4 and 11). DNA synthesis, alkaline phosphatase (ALP) activity, iii osteopontin synthesis and collagen synthesis were determined. Results indicate that culture in the presence of Zr-ACP significantly increased cell proliferation, ALP activity and osteopontin synthesis but not collagen synthesis. To determine the feasibility of incorporating Zr-ACP into a PLGA scaffold, PLGA/Zr-ACP composite foams (5% or 10% (w/v) polymer:solvent with 25 wt% or 50 wt% Zr-ACP) were fabricated using a thermal phase inversion technique. Scanning electron microscopy revealed a highly porous structure with pores ranging in size from a few microns to about 100 µm. The amorphous structure of the Zr-ACP was maintained during composite fabrication as confirmed by X-ray diffraction measurements. Composite scaffolds also showed significantly greater compressive yield strengths and moduli as compared to pure polymer scaffolds.The results of this study indicate that Zr-ACP enhances the osteoblastic phenotype of MC3T3-E1 cells in vitro and can be incorporated into a porous PLGA scaffold. Porous PLGA/Zr-ACP composites are promising for use as bone scaffolds to heal bone defects.iv

show abstract

Section: Ceramicsmentioning

confidence: 99%

Osteoblast response to zirconia‐hybridized pyrophosphate‐stabilized amorphous calcium phosphate

Whited

Škrtić

Love

et al. 2005

J Biomedical Materials Res

View full text Add to dashboard Cite

show abstract

“…Studies of calcium polyphosphate (CPP-[Ca(PO 3 ) 2 ] n ) for preparation of porous bulk constructs intended as biodegradable bone substitutes and biphasic implants for osteochondral defect repair have been reported previously [1][2][3][4][5][6][7]. A study of CPP particulates for use as bone void fillers in non-or minimally-loaded sites has also been reported recently [8].…”

Section: Introductionmentioning

confidence: 99%

Phase transformations during processing and in vitro degradation of porous calcium polyphosphates

Pilliar

Grynpas

et al. 2016

J Mater Sci: Mater Med

View full text Add to dashboard Cite

A 2-Step sinter/anneal treatment has been reported previously for forming porous CPP as biodegradable bone substitutes [9]. During the 2-Step annealing treatment, the heat treatment used strongly affected the rate of CPP degradation in vitro. In the present study, x-ray diffraction and (31)P solid state nuclear magnetic resonance were used to determine the phases that formed using different heat treating processes. The effect of in vitro degradation (in PBS at 37 °C, pH 7.1 or 4.5) was also studied. During CPP preparation, β-CPP and γ-CPP were identified in powders formed from a calcium monobasic monohydrate precursor after an initial calcining treatment (10 h at 500 °C). Melting of this CPP powder (at 1100 °C), quenching and grinding formed amorphous CPP powders. Annealing powders at 585 °C (Step-1) resulted in rapid sintering to form amorphous porous CPP. Continued annealing to 650 °C resulted in crystallization to form a multi-phase structure of β-CPP primarily plus lesser amounts of α-CPP, calcium ultra-phosphates and retained amorphous CPP. Annealing above 720 °C and up to 950 °C transformed this to β-CPP phase. In vitro degradation of the 585 °C (Step-1 only) and 650 °C Step-2 annealed multi-phase samples occurred significantly faster than the β-CPP samples formed by Step-2 annealing at or above 720 °C. This faster degradation was attributable to preferential degradation of thermodynamically less stable phases that formed in samples annealed at 650 °C (i.e. α-phase, ultra-phosphate and amorphous CPP). Degradation in lower pH solutions significantly increased degradation rates of the 585 and 650 °C annealed samples but had no significant effect on the β-CPP samples.

show abstract

“…31,33,34 However, Grynpas et al 33 noted that oversized pores not only reduce mechanical strength but also influence cell function and new bone formation. High levels of interconnectivity between the pores enhance the porosity and enlarge the superficial area and consequently increase the numbers of endothelial cells and active osteoblasts.…”

mentioning

confidence: 99%

Angiogenesis and bone regeneration of porous nano-hydroxyapatite/coralline blocks coated with rhVEGF165 in critical-size alveolar bone defects in vivo

Du¹,

Liu²,

Deng³

et al. 2015

IJN

View full text Add to dashboard Cite

To improve the regenerative performance of nano-hydroxyapatite/coralline (nHA/coral) block grafting in a canine mandibular critical-size defect model, nHA/coral blocks were coated with recombinant human vascular endothelial growth factor 165 (rhVEGF) via physical adsorption (3 μg rhVEGF 165 per nHA/coral block). After the nHA/coral blocks and VEGF/nHA/coral blocks were randomly implanted into the mandibular box-shaped defects in a split-mouth design, the healing process was evaluated by histological observation and histomorphometric and immunohistological analyses. The histological evaluations revealed the ingrowth of newly formed blood vessels and bone at the periphery and cores of the blocks in both groups at both 3 and 8 weeks postsurgery, respectively. In the histomorphometric analysis, the VEGF/nHA/coral group exhibited a larger quantity of new bone formation at 3 and 8 weeks postsurgery. The percentages of newly formed bone within the entire blocks in the VEGF/nHA/coral group were 27.3%±8.1% and 39.3%±12.8% at 3 weeks and 8 weeks, respectively, and these values were slightly greater than those of the nHA/coral group (21.7%±3.0% and 32.6%±10.3%, respectively), but the differences were not significant ( P >0.05). The immunohistological evaluations revealed that the neovascular density in the VEGF/nHA/coral group (146±32.9 vessel/mm 2 ) was much greater than that in the nHA/coral group (105±51.8 vessel/mm 2 ) at the 3-week time point ( P <0.05), but no significant difference was observed at the 8-week time point (341±86.1 and 269±50.7 vessel/mm 2 , respectively, P >0.05). The present study indicated that nHA/coral blocks might be optimal scaffolds for block grafting in critical-size mandibular defects and that additional VEGF coating via physical adsorption can promote angiogenesis in the early stage of bone healing, which suggests that prevascularized nHA/coral blocks have significant potential as a bioactive material for bone regeneration in large-scale alveolar defects.

show abstract

Porous calcium polyphosphate scaffolds for bone substitute applications in vivo studies

Cited by 173 publications

References 10 publications

Osteoblast response to zirconia‐hybridized pyrophosphate‐stabilized amorphous calcium phosphate

Osteoblast response to zirconia‐hybridized pyrophosphate‐stabilized amorphous calcium phosphate

Phase transformations during processing and in vitro degradation of porous calcium polyphosphates

Angiogenesis and bone regeneration of porous nano-hydroxyapatite/coralline blocks coated with rhVEGF165 in critical-size alveolar bone defects in vivo

Contact Info

Product

Resources

About