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PubMed1998

Polymer concepts in tissue engineering.

Traumatic injuries, cancer treatment, and congenital abnormalities are often associated with abnormal bone shape or segmental bone loss. Restoration of normal structure and function in these cases requires replacement of the missing bone that may be accomplished by surgical transfer of natural tissue from an uninjured location elsewhere in the body. However, this procedure is limited by availability, adequate blood supply, and secondary deformities at the donor site. One strategy to overcome these problems is to develop living tissue substitutes based on synthetic biodegradable polymers. Three methods of bone regeneration using biodegradable polymers are being studied in our laboratory: tissue induction, cell transplantation, and fabrication of vascularized bone flaps. Injectable polymers are used for filling skeletal defects and guiding bone tissue growth. Their main advantage is minimizing the surgical intervention or the severity of the surgery. Polymer-cell constructs also hold great promise in the field of tissue engineering. They provide a scaffold on which cells grow and organize themselves. As the cells begin to secrete their own extracellular matrix, the polymer degrades and is eventually eliminated from the body, resulting in completely natural tissue replacement. Bone flaps can be fabricated ectopically into precise shapes and sizes. With an attached vascular supply, these flaps can be transferred into areas deficient in vascularity. This article discusses polymer concepts regarding bone tissue engineering and reviews recent advances of our laboratory on guided bone regeneration using biodegradable polymer scaffolds.

Animals↗

PubMed1998

Surface characteristics and biocompatibility of lactide-based poly(ethylene glycol) scaffolds for tissue engineering.

Novel lactide-based poly(ethylene glycol) (PEG) polymer networks (GL9-PEGs) were prepared by UV copolymerization of a glycerol-lactide triacrylate (GL9-Ac) with PEG monoacrylate (PEG-Ac) to use as scaffolds in tissue engineering, and the surface properties and biocompatibility of these networks were investigated as a function of PEG molecular weight and content. Analysis by ATR-FTIR and ESCA revealed that PEG was incorporated well within the GL9-PEG polymer networks and was enriched at the surfaces. From the results of SEM, AFM, and contact angle analyses, GL9-PEG networks showed relatively rough and irregular surfaces compared to GL9 network, but the mobile PEG chains coupled at their termini were readily exposed toward the aqueous environment when contacting water such that the surfaces became smoother and more hydrophilic. This reorientation and increase in hydrophilicity were more extensive with increasing PEG molecular weight and content. As compared to GL9 network lacking PEG, protein adsorption as well as platelet and S. epidermidis adhesion to GL9-PEG networks were significantly reduced as the molecular weight and content of PEG was increased, indicating that GL9-PEG networks are more biocompatible than the GL9 network due to PEG's passivity. Based on the physical and biological characterization reported, the GL9-PEG materials would appear to be interesting candidates as matrices for tissue engineering.

Bacterial Adhesion↗

PubMedDate not supplied

Design and fabrication of biodegradable polymer devices to engineer tubular tissues.

Engineering new tissues by transplanting cells on polymeric delivery devices is one approach to alleviate the vast shortage of donor tissue. However, it will be necessary to fabricate cell delivery devices that deliver cells to a given location and promote the formation of specific tissue structures from the transplanted cells and the host tissue. This report describes the design and fabrication of a polymeric device for guiding the development of tubular vascularized tissues, which may be useful for engineering a variety of tissues including intestine, blood vessels, tracheas, and ureters. Porous films of poly (D, L-lactic-co-glycolic acid) have been formed and fabricated into tubes capable of resisting compressional forces in vitro and in vivo. These devices promote the ingrowth of fibrovascular tissue following implantation into recipient animals, resulting in a vascularized, tubular tissue. To investigate the utility of these devices as cell delivery devices, enterocytes (intestinal epithelial cells) were seeded onto the devices in vitro. Enterocytes were found to attach to these devices and form an organized epithelial cell layer. These results suggest that these devices may be an appropriate delivery vehicle for transplanting cells and engineering new tubular tissues.

Animals↗

PubMed1998

Cartilage tissue engineering with novel nonwoven structured biomaterial based on hyaluronic acid benzyl ester.

The aim of this study was to investigate the possibility of using the benzyl ester of hyaluronic acid (HYAFF 11), a recently developed semisynthetic resorbable material, as a scaffold for the culture of human nasoseptal chondrocytes in tissue-engineering procedures of cartilage reconstruction. Different techniques such as immunohistochemistry, scanning electron microscopy, and confocal laser scanning microscopy were used to study the behavior, morphology, and phenotype expression of the chondrocytes, which were initially expanded and then seeded on the material. The nonwoven cell carrier allowed good viability and adhesivity of the cells without any surface treatment with additional substances. Furthermore, the cultured cells expressed cartilage-specific collagen type II, indicating that they were able to redifferentiate within the scaffold of HYAFF 11 and were able to retain a chondrocyte phenotype even after a long period of in vitro conditions. Nevertheless, the expression of collagen type I, which was produced by dedifferentiated or incompletely redifferentiated chondrocytes, was noticeable. Additional data were obtained by subcutaneous implantation of samples seeded with human cells in the in vivo model of the athymic nude mouse. The results after 1 month revealed the development of tissue similar to hyaline cartilage. This study is promising for the use of this scaffold for tissue engineering of cartilage replacements.

Animals↗

PubMed1998

In vitro reconstruction of a human capillary-like network in a tissue-engineered skin equivalent.

For patients with extensive burns, wound coverage with an autologous in vitro reconstructed skin made of both dermis and epidermis should be the best alternative to split-thickness graft. Unfortunately, various obstacles have delayed the widespread use of composite skin substitutes. Insufficient vascularization has been proposed as the most likely reason for their unreliable survival. Our purpose was to develop a vascular-like network inside tissue-engineered skin in order to improve graft vascularization. To reach this aim, we fabricated a collagen biopolymer in which three human cell types keratinocytes, dermal fibroblasts, and umbilical vein endothelial cells were cocultured. We demonstrated that the endothelialized skin equivalent (ESE) promoted spontaneous formation of capillary-like structures in a highly differentiated extracellular matrix. Immunohistochemical analysis and transmission electron microscopy of the ESE showed characteristics associated with the microvasculature in vivo (von Willebrand factor, Weibel-Palade bodies, basement membrane material, and intercellular junctions). We have developed the first endothelialized human tissue-engineered skin in which a network of capillary-like tubes is formed. The transplantation of this ESE on human should accelerate graft revascularization by inosculation of its preexisting capillary-like network with the patient's own blood vessels, as it is observed with autografts. In addition, the ESE turns out to be a promising in vitro angiogenesis model.

Basement Membrane↗

PubMed1995

Tissue engineered perivascular endothelial cell implants regulate vascular injury.

Molecular biomaterial engineering permits in vivo transplantation of cells and tissues, offering the promise of restoration of physiologic control rather than pharmacologic dosing with isolated compounds. We engrafted endothelial cells on Gelfoam biopolymeric matrices with retention of viability, normal growth kinetics, immunoreactivity, and biochemical activity. The production of heparan sulfate proteoglycan and inhibition of basic fibroblast growth factor binding and activity by engrafted cells were indistinguishable from endothelial cells grown in culture. Perivascular implantation of Gelfoam-endothelial cell scaffolds around balloon-denuded rat carotid arteries reduced intimal hyperplasia 88.1%, far better than the isolated administration of heparin, the most effective endothelial mimic compound. In concert with a reduction in intimal area, cell proliferation was reduced by > 90%. To our knowledge, there have been no previous reports of extravascular cell implants controlling vasculoproliferative disease. Tissue engineered cells offer the potential for potent methods of vascular growth regulation and insight into the complex autocrine-paracrine control mechanisms within the blood vessel wall.

Animals↗

PubMed1998

Prevention of focal intimal hyperplasia in rat vein grafts by using a tissue engineering approach.

The present study focused on the role of blood flow in the formation of focal intimal hyperplasia in vein grafts, as well as the development of an engineering approach that can be used to eliminate disturbed blood flow and prevent blood flow-related focal intimal hyperplasia. A rat vein graft model was constructed by interposing a jugular vein into the abdominal aorta with end-to-end anastomoses. Locally disturbed flow was identified by analyzing particle streak-lines in methyl salicylate-cleared and perfused vein grafts in vitro with a physiological Reynolds number. At day 10, 20, and 30 after surgery, focal intimal hyperplasia of the vein grafts was examined using a histological approach and the density of alpha-actin positive cells was determined using immunohistological and fluorescent approaches. Results showed that apparent eddy blood flow formed at the proximal, but not at the distal, end of the vein grafts due to graft-host diameter mismatch and local geometric distortions, and was associated with apparent focal intimal hyperplasia. The thickness of the alpha-actin positive layers of the proximal vein grafts was significantly higher than that of the distal grafts (192 +/- 27 vs. 94 +/- 18 microm, 278 +/- 55 vs. 124 +/- 20 microm, and 288 +/- 24 vs. 131 +/- 23 microm for day 10, 20. and 30, respectively). The density of the alpha-actin positive cells, however, was similar between the proximal and the distal regions (3569 +/- 361 vs. 3285 +/- 343 cells/mm2, 5540 +/- 650 vs. 5376 + 887 cells/mm2, and 5465 +/- 791 vs. 5278 +/- 524 cells/mm2 for day 10, 20, and 30, respectively). When eddy blood flow was eliminated by matching the graft-host diameters using a tissue engineering approach, the average thickness of the alpha-actin positive layers of the proximal (71 +/- 15, 86 +/- 16, and 85 +/- 14 microm for day 10, 20, and 30, respectively) and the distal vein grafts (68 +/- 13, 80 +/- 14, and 79 +/- 13 microm for day 10, 20, and 30, respectively) was reduced significantly. The density of the alpha-actin positive cells was also reduced significantly in the proximal (2946 +/- 359, 3261 +/- 295, 3472 +/- 599 cells/mm2 for day 10, 20, and 30, respectively) and in the distal regions (3151 +/- 511, 3466 +/- 687, 3593 +/- 688 cells/mm2 for day 10, 20, and 30, respectively). The thickness of the alpha-actin positive layers and the density of the alpha-actin positive cells were not significantly different between the proximal and distal regions of the engineered vein grafts at each observation time. These results suggest that eddy flow may develop in vein grafts and may facilitate the formation of focal intimal hyperplasia, and the vascular tissue engineering approach developed in this study may be used to prevent blood flow-related focal intimal hyperplasia in vein grafts.

Actins↗

PubMed1994

Bone defect repair with tissue-engineered cartilage.

We tested the efficacy of a new approach for the tissue-engineered growth of cartilage developed in our laboratory in repairing surgically created bone defects in the craniums of rats. Large cranial defects were created bilaterally in the frontoparietotemporal bones of athymic nude rats (n = 10). There was gross evidence of new cartilage in 8 of 10 experimental defects that had been filled with a synthetic biocompatible, biodegradable polymer template that had been seeded in vitro with freshly isolated chondrocytes. The control defects, filled with either nothing at all or a polymer template without chondrocytes, showed no evidence of cartilaginous repair (0 of 10). Statistical analysis using McNemar's test with pooled samples showed significant differences between the two groups (p < 0.05). Prior reports concerning the biologic repair of bony defects involved stimulation of adjacent mesenchymal tissue and resulted in ingrowth of new bone. To our knowledge, this is the first report of structural cartilaginous repair of a bony defect with matrix secreted by implanted chondrocytes.

Animals↗

PubMed1997

The in vitro construction of a tissue engineered bioprosthetic heart valve.

PROBLEM: Heart valve replacement with either a nonliving xenograft or a mechanical prosthesis is an effective therapy for valvular heart disease. Both of these approaches have limitations, including their inability to grow, repair, and remodel. In addition, a mechanical prosthesis requires long-term anticoagulation therapy. METHODS: This study demonstrates the in vitro creation of tissue engineered heart valve tissue using cardiovascular cells on degradable polymer matrices, 40 heart valve leaflets were created using this technique from two sources. Xenograft leaflets were created using human dermal fibroblasts and bovine aortic endothelial cells (n = 20) or allograft valve leaflets were created using sheep myofibroblasts and sheep endothelial cells (n = 20). A mixed sheep cell population was obtained consisting of endothelial cells and myofibroblasts. Endothelial cells were labelled with acethylated low density lipoprotein (Ac-Dil-LDL) and cells were separated into two groups using an activated cell sorter: LDL positive cells comprised of a pure endothelial cell population and LDL negative cells comprised of mixed cell population containing myofibroblasts and smooth muscle cells. The LDL negative cells were seeded on a synthetic polyglycolic acid (PGA) mesh and grown in vitro to form a tissue-like fibroblast-mesh core. Endothelial cells were then seeded onto the surface of the fibroblast-mesh core, forming a single monolayer. RESULTS: Histological evaluation of these constructs revealed an inner core of LDL negative cells and outer endothelial-like cells which were factor VIII positive. There was no evidence of capillary formation from endothelial cells invading the myofibroblasts and smooth muscle matrix and the endothelial lining appeared complete. CONCLUSIONS: It is feasible to construct allogenic heart valve tissue which could be used to make a valve.

Animals↗

PubMed1998

Tissue-engineered nipple reconstruction.

We describe a simple, effective approach to the creation of autologous tissue-engineered cartilage in the shape of a human nipple by injecting a reverse thermosensitive polymer seeded with autologous chondrocytes in an immunocompetent porcine animal model. A biodegradable, biocompatible copolymer of polyethylene oxide and polypropylene oxide (Pluronic F-127), which exists as a liquid below 4 degrees C and polymerizes to a thick gel when it is exposed to physiologic temperatures (body temperatures), was used as a vehicle for chondrocyte delivery and as a scaffold to guide growth. Autologous chondrocytes isolated from porcine auricular elastic cartilage and suspended in 30% (weight/volume) Pluronic F-127 were injected on the ventral surface of the pigs from which the cells had been isolated. A circumferential subdermal suture was used to support the contour of the implant and assist in its projection in the form of a human nipple. After 3 weeks, the skin over and surrounding the implant was tattooed to create the appearance of a human nipple-areolar complex. As controls, an equal number of injections were made using either cells alone (not suspended in hydrogel), or hydrogel alone. After 10 weeks, all specimens were excised and examined both grossly and histologically. Before harvesting, visual inspection of the tattooed chondrocyte-Pluronic F-127 hydrogel implant sites revealed that they closely resembled a human female nipple-areolar complex. Nodules were similar in size, shape, and texture to a human nipple at each injection site. Glistening opalescent tissue was surgically isolated from each implant site. Hematoxylin and eosin, safranine o, trichrome blue, and Verhoeff's stains of the experimental implants showed nodules with the characteristic histologic signs of elastic cartilage. Control injections of copolymer hydrogel alone exhibited no evidence of cartilage formation. Control injections of chondrocytes alone showed evidence of dissociated microscopic nodules of elastic cartilage.

Animals↗

PubMed1998

Bioreactor perfusion system for the long-term maintenance of tissue-engineered skeletal muscle organoids.

Three-dimensional skeletal muscle organ-like structures (organoids) formed in tissue culture by fusion of proliferating myoblasts into parallel networks of long, unbranched myofibers provide an in vivo-like model for examining the effects of growth factors, tension, and space flight on muscle cell growth and metabolism. To determine the feasibility of maintaining either avian or mammalian muscle organoids in a commercial perfusion bioreactor system, we measured metabolism, protein turnover. and autocrine/paracrine growth factor release rates. Medium glucose was metabolized at a constant rate in both low-serum- and serum-free media for up to 30 d. Total organoid noncollagenous protein and DNA content decreased approximately 22-28% (P < 0.05) over a 13-d period. Total protein synthesis rates could be determined accurately in the bioreactors for up to 30 h and total protein degradation rates could be measured for up to 3 wk. Special fixation and storage conditions necessary for space flight studies were validated as part of the studies. For example, the anabolic autocrine/paracrine skeletal muscle growth factors prostaglandin F2alpha (PGF2alpha) and insulin-like growth factor-1 (IGF-1) could be measured accurately in collected media fractions, even after storage at 37 degrees C for up to 10 d. In contrast, creatine kinase activity (a marker of cell damage) in collected media fractions was unreliable. These results provide initial benchmarks for long-term ex vivo studies of tissue-engineered skeletal muscle.

Animals↗

PubMed1997

Transplantation of chondrocytes utilizing a polymer-cell construct to produce tissue-engineered cartilage in the shape of a human ear.

This study evaluates the feasibility of growing tissue-engineered cartilage in the shape of a human ear using chondrocytes seeded onto a synthetic biodegradable polymer fashioned in the shape of a 3-year-old child's auricle. A polymer template was formed in the shape of a human auricle using a nonwoven mesh of polyglycolic acid molded after being immersed in a 1% solution of polylactic acid. Each polyglycolic acid-polylactic acid template was seeded with chondrocytes isolated from bovine articular cartilage and then implanted into subcutaneous pockets on the dorsa of 10 athymic mice. The three-dimensional structure was well maintained after removal of an external stent that had been applied for 4 weeks. Specimens harvested 12 weeks after implantation and subjected to gross morphologic and histologic analysis demonstrated new cartilage formation. The overall geometry of the experimental specimens closely resembled the complex structure of the child's auricle. These findings demonstrate that polyglycolic acid-polylactic acid constructs can be fabricated in a very intricate configuration and seeded with chondrocytes to generate new cartilage that would be useful in plastic and reconstructive surgery.

Animals↗

PubMedDate not supplied

Development of technologies aiding large-tissue engineering.

There are many clinical situations in which a large tissue mass is required to replace tissue lost to surgical resection (e.g., mastectomy). It is possible that autologous cell transplantation on biodegradable polymer matrices may provide a new therapy to engineer large tissue which can be used to treat these patients. A number of challenges must be met to engineer a large soft tissue mass. These include the design of (1) a structural framework to maintain a space for tissue development, (2) a space-filling matrix which provides for localization of transplanted cells, and (3) a strategy to enhance vascularization of the forming tissue. In this paper we provide an overview of several technologies which are under development to address these issues. Specifically, support matrices to maintain a space for tissue development have been fabricated from polymers of lactide and glycolide. The ability of these structures to resist compressive forces was regulated by the ratio of lactide to glycolide in the polymer. Smooth muscle cell seeding onto polyglycolide fiber-based matrices has been optimized to allow formation of new tissues in vitro and in vivo. Finally, polymer microsphere drug delivery technology is being developed to release vascular endothelial growth factor (VEGF), a potent angiogenic molecule, at the site of tissue formation. This strategy, which combines several different technologies, may ultimately allow for the engineering of large soft tissues.

Animals↗

PubMed1998

Cartilage reconstruction in head and neck surgery: comparison of resorbable polymer scaffolds for tissue engineering of human septal cartilage.

New cell culture techniques raise the possibility of creating cartilage in vitro with the help of tissue engineering. In this study, we compared two resorbable nonwoven cell scaffolds, a polyglycolic acid/poly-L-lactic acid (PGA/PLLA) (90/10) copolymer (Ethisorb) and pure PLLA (V 7-2), with different degradation characteristics in their aptitude for cartilage reconstruction. Chondrocytes were isolated enzymatically from human septal cartilage. The single cells were resuspended in agarose and transferred into the polymer scaffolds to create mechanical stability and retain the chondrocyte-specific phenotype. The cell-polymer constructs were then kept in perfusion culture for 1 week prior to subcutaneous transplantation into thymusaplastic nude mice. After 6, 12, and 24 weeks, the specimens were explanted and analyzed histochemically on the presence of collagen (azan staining), proteoglycans (Alcian blue staining), and calcification areas (von Kossa staining). Furthermore, different collagen types (collagen type I, which is found in most tissues, but not in hyaline cartilage matrix; and collagen type II, which is cartilage specific) were differentiated immunohistochemically by the indirect immunoperoxidase technique. Vascular ingrowth was investigated by a factor VIII antibody, which is a endothelial marker. Quantification of several matrix components was performed using the software Photoshop. Significant differences were found between both nonwoven structures concerning matrix synthesis and matrix quality as well as vascular ingrowth. Ethisorb, with a degradation time of approximately 3 weeks in vitro, showed no significant differences from normal human septal cartilage in the amount of collagen types I and II 24 weeks after transplantation. Thin fibrous tissue layers containing blood vessels encapsulated the transplants. V 7-2 constructs, which did not show strong signs of degradation even 24 weeks after transplantation, contained remarkably smaller amounts of cartilage-specific matrix components. At the same time, there was vascular ingrowth even in central parts of the transplants. In conclusion, polymer scaffolds with a short degradation time are suitable materials for the development of cartilage matrix products, while longer stability seems to inhibit matrix synthesis. Thus, in vitro engineering of human cartilage can result in a cartilage-like tissue when appropriate nonwovens are used. Therefore, this method could be the ideal cartilage replacement method without the risk of infection and with the possibility of reconstructing large defects with different configurations.

Adult↗

PubMed1998

Tissue engineering: a new approach in cardiovascular surgery: Seeding of human fibroblasts followed by human endothelial cells on resorbable mesh.

OBJECTIVE: In tissue engineering the material properties of synthetic compounds are chosen to enable delivery of dissociated cells onto a scaffold in a manner that will result in in vitro formation of a new functional tissue. The seeding of human fibroblasts followed by human endothelial cells on resorbable mesh is a precondition of a successful creation of human tissues such as vessels or cardiac valves. METHODS: Polymeric scaffolds (n = 18) composed of polyglycolic acid (PGA) with a fiber diameter of 12-15 microm and a polymer density of 70 mg/ml were used as square sheets of 1 x 1 x 0.3 cm. Fibroblasts (passage 7) harvested from human foreskin were seeded (3.4 x 10(6)) and cultured over a 3 week period on a PGA-mesh, followed by seeding of endothelial cells (passage 5, 2.8 x 10(6)) harvested from human ascending aorta. Thereafter the new tissue was stained for HE, van Gieson, Trichrom Masson, Factor VIII and CD 34 and proved by scanning electron microscopy. RESULTS: Microscopic examination of the seeded mesh demonstrated that the human fibroblasts were attached to the polymeric fibers and had begun to spread out and divide. The scanning electron microscopic examination demonstrated a homogeneous scaffold resembling a solid sheet of tissue. The seeded endothelial cells formed a monolayer on the fibroblasts and no endothelial cell invasion or new formation of capillaris could be detected. CONCLUSIONS: These results are a first step to demonstrate that seeding of human fibroblasts and endothelial cells on PGA-mesh might be a feasible model to construct human tissues such as vessels or cardiac valves.

Aorta↗

PubMed1998

Tissue engineered skin: Apligraf, a bi-layered living skin equivalent.

Driven by the need for a readily available, non-immunological tissue that possesses many of the characteristics of normal human skin, tissue-engineered skin has been developed. For over a decade, laboratory grown or processed skin has been under investigation and, in some cases, available as an alternative to autologous grafts. Apligraf, derived from neonatal foreskin and bovine type I collagen, is the first bi-layered living skin equivalent approved in the US and other countries for use in venous ulcers. Apligraf is effective both in the treatment of refractory venous ulcers and for acute wounds such as surgical excision sites and split thickness donor sites. Apligraf is safe and is not clinically rejected. Its ultimate fate is not known, so it may well work to aid healing in a variety of ways including graft 'take' and as a stimulus for healing.

Animals↗

PubMed1996

Tissue engineering scaffolds using superstructures.

Here, scaffolds as cell and tissue carriers are approached from an engineering point of view, emphasizing material superstructuring in the design of supports. Superstructure engineering provides optimal spatial and nutritional conditions for cell maintenance by the arrangement of structural elements (e.g. pores or fibres) so as to vary the order of cell to cell contact. This approach is illustrated in the design of several scaffolds: knitted fabrics as three-dimensional superstructures for optimized osteosynthesis implants, a new injectable open porous implant system, an angiopolar non-degradable ceramic cell carrier, and an injectable or microsurgically implantable entangled carrier system. The implications for tissue engineering are discussed.

Anisotropy↗

PubMed1996

Tissue engineered bone-regeneration using degradable polymers: the formation of mineralized matrices.

In the development of 3-dimensional cell-polymer matrices for tissue engineering, the ability of osteoblast cells to maintain their phenotypic properties and form a mineralized matrix while seeded on the polymer surface is very important. Osteoblast cell differentiation and bone formation using rat calvaria cells were studied on the surface of a porous poly(lactide/glycolide)/hydroxyapatite (PLAGA/HA) 3-dimensional polymer matrix. Cell adhesion and proliferation were determined at 24 hr, 3, 7, 14, and 21 days. Cell attachment and proliferation were observed to increase throughout the first two weeks of the study, followed by a period of gradual plateauing of cell numbers. Environmental scanning electron microscopy demonstrated that cells grown on the surface of the 3-dimensional porous PLAGA/HA matrix retained their characteristic morphology and grew in a multi-layer fashion. Light microscopy observations of experiment cultures revealed active osteoblastic cells forming a characteristic mineralized matrix in the presence of beta-glycerophosphate as a phosphate donor. Mineralization did not occur in media either not supplemented with beta-glycerophosphate or when the matrix without cells was incubated with the reagents, indicating that the mineralization was due to the cells and not the HA in the matrix. These results suggest that the 3-dimensional PLAGA/HA matrix could provide a matrix for bone cell differentiation and mineralization in vitro and, therefore, may be a candidate as a synthetic implant for bone regeneration.

Animals↗