Tricalcium phosphate and glutaraldehyde crosslinked gelatin incorporating bone morphogenetic protein--a viable scaffold for bone tissue engineering

Combination of human platelet lysate and 3D gelatin scaffolds to enhance osteogenic differentiation of human amniotic fluid derived mesenchymal stem cells

Bone disorders are major health issues requiring specialized care; however, the traditional bone grafting method had several limitations. Thus, bone tissue engineering has become a potential alternative. In therapeutic treatments, using fetal bovine serum (FBS) as a culture supplement may result in the risk of contamination and host immunological response; therefore, human platelet lysate (hPL) has been considered a viable alternative source. This study attempted to compare the effectiveness and safety of different culture supplements, either FBS or hPL, on the osteoblastic differentiation potential of mesenchymal stem cells derived from human amniotic fluid (hAF-MSCs) under a three-dimensional gelatin scaffold. The results indicate that hAF-MSCs have the potential to be used in clinical applications as they meet the criteria for mesenchymal stem cells based on their morphology, the expression of a particular surface antigen, their proliferation ability, and their capacity for multipotent differentiation. After evaluation by MTT and Alamar blue proliferation assay, 10% of hPL was selected. The osteogenic differentiation of hAF-MSCs under three-dimensional gelatin scaffold using osteogenic-induced media supplemented with hPL was achievable and markedly stimulated osteoblast differentiation. Moreover, the expressions of osteoblastogenic related genes, including OCN, ALP, and COL1A1, exhibited the highest degree of expression under hPL-supplemented circumstances when compared with the control and the FBS-supplemented group. The induced cells under hPL-supplemented conditions also presented the highest ALP activity level and the greatest degree of calcium accumulation. These outcomes would indicate that hPL is a suitable substitute for animal derived serum. Importantly, osteogenic differentiation of human amniotic fluid derived mesenchymal stem cells using hPL-supplemented media and three-dimensional scaffolds may open the door to developing an alternative construct for repairing bone defects.

Clinical and radiographic study of the use of cross-linked gelfoam matrix in the treatment of dehiscence-like defects in Stage III periodontitis

Background

This clinical study aimed to overcome the difficulty of graft fixation and limited blood supply for dehiscence defects regeneration by using a cross-linked gelfoam matrix jointly with collagen membrane and xenograft.

Materials and Methods

The study included twenty dehiscence-like defects in maxillary anterior teeth with ≥4 mm facial bone loss and ≥5 mm clinical attachment loss (CAL) in patients suffering from Stage III periodontitis. Sites were treated with regenerative surgery using a cross-linked gelfoam matrix with glutaraldehyde, xenograft, and collagen membrane. The recorded parameters were: CAL, probing pocket depth (PPD), and radiographic three-dimensional (3D) volume for dehiscence-like defects (3D volume of facial bone defects) and 3D volume of interproximal defects using cone-beam radiographs. Data of these parameters were collected at both baseline and 6 months postsurgery. "Paired t-test" was used to assess the two variables."

Results

Both CAL and PPD showed statistically significant reductions and there was a significant bone gain at 6 months postsurgery in comparison to baseline (P ≤ 0.05).

Conclusion

Using a cross-linked gelfoam matrix with glutaraldehyde in combination with xenograft and collagen membrane could enhance the outcome of periodontal regeneration, especially in the treatment of challenging dehiscence defects.

An Overview on Collagen and Gelatin-Based Cryogels: Fabrication, Classification, Properties and Biomedical Applications

Decades of research into cryogels have resulted in the development of many types of cryogels for various applications. Collagen and gelatin possess nontoxicity, intrinsic gel-forming ability and physicochemical properties, and excellent biocompatibility and biodegradability, making them very desirable candidates for the fabrication of cryogels. Collagen-based cryogels (CBCs) and gelatin-based cryogels (GBCs) have been successfully applied as three-dimensional substrates for cell culture and have shown promise for biomedical use. A key point in the development of CBCs and GBCs is the quantitative and precise characterization of their properties and their correlation with preparation process and parameters, enabling these cryogels to be tuned to match engineering requirements. Great efforts have been devoted to fabricating these types of cryogels and exploring their potential biomedical application. However, to the best of our knowledge, no comprehensive overviews focused on CBCs and GBCs have been reported currently. In this review, we attempt to provide insight into the recent advances on such kinds of cryogels, including their fabrication methods and structural properties, as well as potential biomedical applications.

Crosslinking of gum-based composite scaffolds for enhanced strength and stability: A comparative study between sodium trimetaphosphate and glutaraldehyde

Tissue engineering is one of the potential fields in the domain of regenerative medicine. Engineered scaffolds are an excellent substitute for the conventional use of bone grafts as they are biocompatible, economic, and provide limitless supply with no risk of disease transmission. Gum-based scaffolds present a good scope for studying tissue-engineering models and analyzing controlled drug delivery. Uniform blending of the gums and the presence of the optimal concentration of appropriate crosslinkers are very crucial for biodegradability nature. Gum-based scaffolds containing gellan gum, xanthan gum, polyvinyl alcohol, and hydroxyapatite, cross-linked with either glutaraldehyde (GA) or sodium trimetaphosphate (STMP) were fabricated to study the efficiency of crosslinkers and were characterized for degradation profile, swelling capacity, porosity, mechanical strength, morphology, X-ray diffraction, Fourier-transform infrared, and in vitro biocompatibility. Scaffolds crosslinked with STMP exhibited higher degradation rate at Day 21 than scaffolds crosslinked with GA. However, higher compressive strength was obtained for scaffolds cross-linked with STMP signifying that they have a better ability to resist compressive forces. Superior cell viability was observed in STMP-crosslinked scaffolds. In conclusion, STMP serves as a better crosslinker in comparison to GA and can be used in the fabrication of scaffolds for bone tissue engineering.

Assessment of various crosslinking agents on collagen/chitosan scaffolds for myocardial tissue engineering

Suitable material for scaffolds that support cell attachment, proliferation, vascularization and contraction has always been a challenge in myocardial tissue engineering. Much research effort has been focused on natural polymers including collagen, gelatin, chitosan, fibrin, alginate, etc. Among them, a collagen/chitosan composite scaffold was widely used for myocardial tissue engineering. Due to the non-proliferative and contractile characteristics of cardiomyocytes, the biocompatibility and mechanical properties of the scaffolds are extremely important for supporting intercellular connection and tissue function for myocardial tissue engineering. To the best of our knowledge, the three crosslinking agents (glutaraldehyde (GTA), genipin (GP), tripolyphosphate (TPP)) have not yet been comparatively studied in myocardial tissue engineering. Thus, the aim of this study is to compare and identify the crosslinking effect of GTA, GP and TPP for myocardial tissue engineering. The collagen/chitosan scaffolds prepared with various crosslinking agents were fabricated and evaluated for physical characteristics, biocompatibility and contractile performance. All the groups of scaffolds exhibited high porosity (>65%) and good swelling ratio suitable for myocardial tissue engineering. TPP crosslinked scaffolds showed excellent mechanical properties, with their elastic modulus (81.0 ± 8.1 kPa) in the physiological range of native myocardium (20∼100 kPa). Moreover, GP and TPP crosslinked scaffolds exhibited better biocompatibility than GTA crosslinked scaffolds, as demonstrated by the live/dead staining and proliferation assay. In addition, cardiomyocytes within TPP crosslinked scaffolds showed the highest expression of cardiac-specific marker protein and the best contractile performance. To conclude, of the three crosslinking agents, TPP was recommended as the most suitable crosslinking agent for collagen/chitosan scaffold in myocardial tissue engineering.

Osteostatin potentiates the bioactivity of mesoporous glass scaffolds containing Zn2+ ions in human mesenchymal stem cells

There is an urgent need of biosynthetic bone grafts with enhanced osteogenic capacity. In this study, we describe the design of hierarchical meso-macroporous 3D-scaffolds based on mesoporous bioactive glasses (MBGs), enriched with the peptide osteostatin and Zn2+ ions, and their osteogenic effect on human mesenchymal stem cells (hMSCs) as a preclinical strategy in bone regeneration. The MBG compositions investigated were 80%SiO2-15%CaO-5%P2O5 (in mol-%) Blank (BL), and two analogous glasses containing 4% ZnO (4ZN) and 5% ZnO (5ZN). By using additive fabrication techniques, scaffolds exhibiting hierarchical porosity: mesopores (around 4 nm), macropores (1-600 μm) and big channels (∼1000 μm), were prepared. These MBG scaffolds with or without osteostatin were evaluated in hMCSs cultures. Zinc promoted hMSCs colonization (both the surface and inside) of MBG scaffolds. Moreover, Zn2+ ions and osteostatin together, but not independently, in the scaffolds were found to induce the osteoblast differentiation genes runt related transcription factor-2 (RUNX2) and alkaline phosphatase (ALP) in hMSCs after 7 d of culture in the absence of an osteogenic differentiation-promoting medium. These results add credence to the combined use of zinc and osteostatin as an effective strategy for bone regeneration applications. STATEMENT OF SIGNIFICANCE: Mesoporous bioactive glasses (MBGs) are bioceramics whose unique properties make them excellent materials for bone tissue engineering. Physico-chemical characterization of MBGs as scaffolds made by rapid prototyping, doped with zinc (potential osteogenic, angiogenic and bactericidal ion) and loaded with osteostatin (osteogenic peptide) are described. These Zn-MBGs scaffolds showed 3D hierarchical meso-macroporous structure that enables to host and release osteostatin. When decorated with human mesenchymal stem cells (hMSCs), MBGs scaffoldsenriched with both zinc and osteostatin exhibited a synergistic effect to enhance hMSCs growth, and also hMSCs osteogenic differentiationwithout addition of other osteoblastic differentiation factors to the culture medium. This novel strategy has a great potential for use in bone tissue engineering.

Importance of crosslinking strategies in designing smart biomaterials for bone tissue engineering: A systematic review

Biomaterials are of significant importance in biomedical applications as these biological macromolecules have moderately replaced classical tissue grafting techniques owing to its beneficial properties. Despite of its favourable advantages, poor mechanical and degradative properties of biomaterials are of great concern. To this regard, crosslinkers have emerged as a smart and promising tool to augment the biological functionality of biopolymers. Different crosslinkers have been extensively used in past decades to develop bone substitutes, but the implications of toxic response and adverse reactions are truly precarious after implantation. Traditional crosslinker like glutaraldehyde has been widely used in numerous bio-implants but the potential toxicity is largely being debated with many disproving views. As alternative, green chemicals, enzymatic and non-enzymatic chemicals, bi-functional epoxies, zero-length crosslinkers and physical crosslinkers have been introduced to achieve the desired properties of a bone substitute. In this review, systematic literature search was performed on PubMed database to identify the most commonly used crosslinkers for developing promising bone like materials. The relevant articles were identified, analysed and reviewed in this paper giving due importance to different crosslinking methodologies and comparing their effectiveness and efficacy in regard to material composition, scaffold production, crosslinker dosage, toxicity and immunogenicity. This review summarizes the recent developments in crosslinking mechanism with an emphasis placed on their ability to link proteins through bonding reactions. Finally, this study also covers the convergent and divergent methodologies of crosslinking strategies also giving special importance in retrieving the current limitations and future opportunities of crosslinking modalities in bone tissue engineering.

Calcium Orthophosphate-Containing Biocomposites and Hybrid Biomaterials for Biomedical Applications

The state-of-the-art on calcium orthophosphate (CaPO4)-containing biocomposites and hybrid biomaterials suitable for biomedical applications is presented. Since these types of biomaterials offer many significant and exciting possibilities for hard tissue regeneration, this subject belongs to a rapidly expanding area of biomedical research. Through the successful combinations of the desired properties of matrix materials with those of fillers (in such systems, CaPO4 might play either role), innovative bone graft biomaterials can be designed. Various types of CaPO4-based biocomposites and hybrid biomaterials those are either already in use or being investigated for biomedical applications are extensively discussed. Many different formulations in terms of the material constituents, fabrication technologies, structural and bioactive properties, as well as both in vitro and in vivo characteristics have been already proposed. Among the others, the nano-structurally controlled biocomposites, those containing nanodimensional compounds, biomimetically fabricated formulations with collagen, chitin and/or gelatin, as well as various functionally graded structures seem to be the most promising candidates for clinical applications. The specific advantages of using CaPO4-based biocomposites and hybrid biomaterials in the selected applications are highlighted. As the way from a laboratory to a hospital is a long one and the prospective biomedical candidates have to meet many different necessities, the critical issues and scientific challenges that require further research and development are also examined.

Smart scaffolds in bone tissue engineering: A systematic review of literature

AIM: To improve osteogenic differentiation and attachment of cells.

METHODS: An electronic search was conducted in PubMed from January 2004 to December 2013. Studies which performed smart modifications on conventional bone scaffold materials were included. Scaffolds with controlled release or encapsulation of bioactive molecules were not included. Experiments which did not investigate response of cells toward the scaffold (cell attachment, proliferation or osteoblastic differentiation) were excluded.

RESULTS: Among 1458 studies, 38 met the inclusion and exclusion criteria. The main scaffold varied extensively among the included studies. Smart modifications included addition of growth factors (group I-11 studies), extracellular matrix-like molecules (group II-13 studies) and nanoparticles (nano-HA) (group III-17 studies). In all groups, surface coating was the most commonly applied approach for smart modification of scaffolds. In group I, bone morphogenetic proteins were mainly used as growth factor stabilized on polycaprolactone (PCL). In group II, collagen 1 in combination with PCL, hydroxyapatite (HA) and tricalcium phosphate were the most frequent scaffolds used. In the third group, nano-HA with PCL and chitosan were used the most. As variable methods were used, a thorough and comprehensible compare between the results and approaches was unattainable.

CONCLUSION: Regarding the variability in methodology of these in vitro studies it was demonstrated that smart modification of scaffolds can improve tissue properties.

Sustained delivery of biomolecules from gelatin carriers for applications in bone regeneration

Local delivery of therapeutic biomolecules to stimulate bone regeneration has matured considerably during the past decades, but control over the release of these biomolecules still remains a major challenge. To this end, suitable carriers that allow for tunable spatial and temporal delivery of biomolecules need to be developed. Gelatin is one of the most widely used natural polymers for the controlled and sustained delivery of biomolecules because of its biodegradability, biocompatibility, biosafety and cost–effectiveness. The current study reviews the applications of gelatin as carriers in form of bulk hydrogels, microspheres, nanospheres, colloidal gels and composites for the programmed delivery of commonly used biomolecules for applications in bone regeneration with a specific focus on the relationship between carrier properties and delivery characteristics.

Repairing the osteochondral defect in goat with the tissue-engineered osteochondral graft preconstructed in a double-chamber stirring bioreactor

To investigate the reparative efficacy of tissue-engineered osteochondral (TEO) graft for repairing the osteochondral defect in goat, we designed a double-chamber stirring bioreactor to construct the bone and cartilage composites simultaneously in one β-TCP scaffold and observed the reparative effect in vivo. The osteochondral defects were created in goats and all the animals were divided into 3 groups randomly. In groups A, the defect was treated with the TEO which was cultured with mechanical stimulation of stir; in group B, the defect was treated with TEO which was cultured without mechanical stimulation of stir; in groups C, the defect was treated without TEO. At 12 weeks and 24 weeks after operation, the reparative effects in different groups were assessed and compared. The results indicated that the reparative effect of the TEO cultured in the bioreactor was better than the control group, and mechanical stimulation of stir could further improve the reparative effect. We provided a feasible and effective method to construct the TEO for treatment of osteochondral defect using autologous BMSCs and the double-chamber bioreactor.

Hemostatic gelatin sponge is a superior matrix to matrigel for establishment of LNCaP human prostate cancer in nude mice

BACKGROUND

Matrigels, solubilized basement membrane preparations, are often used to support tumor development in animal models. However, tumors formed by a mixture of tumor cells and Matrigel may vary significantly. The purpose of this study was to compare tumor development and growth of LNCaP human prostate cancer cells mixed with Matrigel or in gelatin sponges.

METHODS

LNCaP cells were mixed with Matrigel or absorbed into VETSPON, a gelatin sponge, and inoculated into the subcutis of nude mice. Tumor incidence and growth rate were determined. Gene expression and cell growth and survival in tumor lesions were evaluated by immunohistochemistry (IHC), immunoblotting, and RT-PCR.

RESULTS

All mice (12/12) inoculated with LNCaP cells in VETSPON produced tumors, compared to 70% (19/27) of mice injected with the cells with Matrigel. Tumor volume also varied less with VETSPON implants. No significant differences were observed in gene expression, cell growth, apoptosis, and microvessel density in tumors established from the two types of implants. However, in samples collected on days 1 and 4, more cells in Matrigel implants than those in VETSPON implants were stained positive for cleaved-caspase 3 and -PARP1. Expression of VEGF-A, HIF-1α, and Bcl-2 was elevated in the early VETSPON implants.

CONCLUSION

These data indicate that VETSPON promotes tumor cell survival at the early stage of implantation and suggest that the gelatin sponge is superior to Matrigel in supporting development and progression of human prostate cancer in nude mice. This model should be useful for preclinical studies in nude mice using LNCaP cells.

Bioceramics: from bone regeneration to cancer nanomedicine

Research on biomaterials has been growing in the last few years due to the clinical needs in organs and tissues replacement and regeneration. In addition, cancer nanomedicine has recently appeared as an effective means to combine nanotechnology developments towards a clinical application. Ceramic materials are suitable candidates to be used in the manufacturing of bone-like scaffolds. Bioceramic materials may also be designed to deliver biologically active substances aimed at repairing, maintaining, restoring or improving the function of organs and tissues in the organism. Several materials such as calcium phosphates, glasses and glass ceramics able to load and subsequently release in a controlled fashion drugs, hormones, growth factors, peptides or nucleic acids have been developed. In particular, to prevent post surgical infections bioceramics may be surface modified and loaded with certain antibiotics, thus preventing the formation of bacterial biofilms. Remarkably, mesoporous bioactive glasses have shown excellent characteristics as drug carrying bone regeneration materials. These bioceramics are not only osteoconductive and osteoproductive, but also osteoinductive, and have therefore been proposed as ideal components for the fabrication of scaffolds for bone tissue engineering. A recent promising development of bioceramic materials is related to the design of magnetic mediators against tumors. Magnetic composites are suitable thermoseeds for cancer treatment by hyperthermia. Moreover, magnetic nanomaterials offer a wide range of possibilities for diagnosis and therapy. These nanoparticles may be conjugated with therapeutic agents and heat the surrounding tissue under the action of alternating magnetic fields, enabling hyperthermia of cancer as an effective adjunct to chemotherapy regimens.

Novel biopolymer-coated hydroxyapatite foams for removing heavy-metals from polluted water

3D-macroporous biopolymer-coated hydroxyapatite (HA) foams have been developed as potential devices for the treatment of lead, cadmium and copper contamination of consumable waters. These foams have exhibited a fast and effective ion metal immobilization into the HA structure after an in vitro treatment mimicking a serious water contamination case. To improve HA foam stability at contaminated aqueous solutions pH, as well as its handling and shape integrity the 3D-macroporous foams have been coated with biopolymers polycaprolactone (PCL) and gelatine cross-linked with glutaraldehyde (G/Glu). Metal ion immobilization tests have shown higher and fast heavy metals captured as function of hydrophilicity rate of biopolymer used. After an in vitro treatment, foam morphology integrity is guaranteed and the uptake of heavy metal ions rises up to 405 μmol/g in the case of Pb(2+), 378 μmol/g of Cu(2+) and 316 μmol/g of Cd(2+). These novel materials promise a feasible advance in development of new, easy to handle and low cost water purifying methods.

Biocomposites and hybrid biomaterials based on calcium orthophosphates

The state-of-the-art of biocomposites and hybrid biomaterials based on calcium orthophosphates that are suitable for biomedical applications is presented in this review. Since these types of biomaterials offer many significant and exciting possibilities for hard tissue regeneration, this subject belongs to a rapidly expanding area of biomedical research. Through successful combinations of the desired properties of matrix materials with those of fillers (in such systems, calcium orthophosphates might play either role), innovative bone graft biomaterials can be designed. Various types of biocomposites and hybrid biomaterials based on calcium orthophosphates, either those already in use or being investigated for biomedical applications, are extensively discussed. Many different formulations, in terms of the material constituents, fabrication technologies, structural and bioactive properties as well as both in vitro and in vivo characteristics, have already been proposed. Among the others, the nanostructurally controlled biocomposites, those containing nanodimensional compounds, biomimetically fabricated formulations with collagen, chitin and/or gelatin as well as various functionally graded structures seem to be the most promising candidates for clinical applications. The specific advantages of using biocomposites and hybrid biomaterials based on calcium orthophosphates in the selected applications are highlighted. As the way from the laboratory to the hospital is a long one, and the prospective biomedical candidates have to meet many different necessities, this review also examines the critical issues and scientific challenges that require further research and development.

Kinetic characterization and comparison of various protein crosslinking reagents for matrix modification

We have characterized the relative efficacies of a number of protein crosslinking agents that have the potential for use in the crosslinking of proteinaceous matrices both in vitro and in vivo. The crosslinkers tested were; L: -threose (LT), Genipin (GP), Methylglyoxal (MG), 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC), proanthrocyanidin (PA) and glutaraldehyde (GA). The relative effectiveness of the crosslinkers with regard to their saturating concentrations was: GA > PA > EDC > MG = GP >> LT. Most of the crosslinkers displayed a pH dependence and were more effective at more alkaline pH. At optimal pH and saturating conditions, the relative reaction rates of the crosslinkers were: PA = GA > EDC > GP > MG >> LT.

From natural bone grafts to tissue engineering therapeutics: Brainstorming on pharmaceutical formulative requirements and challenges

Tissue engineering is an emerging multidisciplinary field of investigation focused on the regeneration of diseased or injured tissues through the delivery of appropriate molecular and mechanical signals. Therefore, bone tissue engineering covers all the attempts to reestablish a normal physiology or to speed up healing of bone in all musculoskeletal disorders and injuries that are lashing modern societies. This article attempts to give a pharmaceutical perspective on the production of engineered man-made bone grafts that are described as implantable tissue engineering therapeutics, and to highlight the importance of understanding bone composition and structure, as well as osteogenesis and bone healing processes, to improve the design and development of such implants. In addition, special emphasis is given to pharmaceutical aspects that are frequently minimized, but that, instead, may be useful for formulation developments and in vitro/in vivo correlations.

Physical approaches to biomaterial design

The development of biomaterials for drug delivery, tissue engineering and medical diagnostics has traditionally been based on new chemistries. However, there is growing recognition that the physical as well as the chemical properties of materials can regulate biological responses. Here, we review this transition with regard to selected physical properties including size, shape, mechanical properties, surface texture and compartmentalization. In each case, we present examples demonstrating the significance of these properties in biology. We also discuss synthesis methods and biological applications for designer biomaterials, which offer unique physical properties.

Gelatin sponges (Gelfoam) as a scaffold for osteoblasts

Gelatine sponge because of its flexibility, biocompatibility, and biodegradability, has the potential to be used as a scaffold to support osteoblasts and to promote bone regeneration in defective areas. This study aimed to determine osteoblast proliferation, differentiation, and integration in modified and un-modified gelatine sponges. Three scaffolds were studied: gelatine sponge (Gelfoam), gelatin sponge/mineral (hydroxyapatite) composite, and gelatin sponge/polymer (poly-lactide-co-glycolide) composite. 2-D plastic coverslip was used as control. The gelatin sponges were modified using PLGA coating and mineral deposition to increase biodegradation resistance and osteoblast proliferation respectively. The scaffolds were characterized using Scanning Electron Microscopy (SEM) and X-ray diffraction. Cell number (DNA content), cell-replication rate (thymidine assay), and cell differentiation (alkaline phosphatase activity) were measured 24 h, 3 days, and 1, 2, 3 weeks after the osteoblast-like cells were cultured onto the scaffolds. Cell penetration into the sponges was determined using haematoxylin-eosin staining. Both modified and unmodified gelatine sponges demonstrated ability to support cell growth and cells were able to penetrate into the sponge pores. In a comparison of different scaffolds, cell number and cell replication were highest in sponge/hydroxyapatite composite and lowest in sponge/PLGA composite.

Mandibular bone repair by implantation of rhBMP-2 in a slow release carrier of polylactic acid--an experimental study in rats

The aim of the present study was to test the hypothesis that human recombinant bone morphogenic protein 2 (rhBMP-2) implanted in a slow release carrier of polylactic acid (PLA) can repair a non-healing defect in the rat mandible and maintain the thickness of an augmented volume. p-DL-lactic acid discs were produced and loaded with 48 and 96 microg rhBMP-2 and inserted into non-healing defects of the mandible of 45 Wistar rats. Fifteen rats received implants with 96 microg rhBMP-2 (Group 2), 48 microg rhBMP-2 (Group 1) and blank implants without BMP (Group 0) each on one side of the mandible. Unfilled defects of the same size on the contralateral sides of the mandibles served as empty controls. After 6, 13 and 26 weeks, implants of each group were retrieved from five animals each and submitted to flat panel detector computed tomography. Bone formation and thickness of augmentation was assessed by computer-assisted histomorphometry. In Group 2 significantly more bone was produced than in Group 1. Implants of Group 1 induced significantly more bone than the blank controls only after 6 weeks, whereas the difference was not significant after 13 and 26 weeks. Differences between Group 2 and Group 1 were clearly significant after 26 weeks. The thickness of bone tissue was maintained in Group 2 whereas it decreased in Group 1 and was negligible in Group 0. It is concluded that the PLA implants with 96 microg rhBMP-2 were able to bridge a non-healing defect in the rat mandible and maintained the thickness of an augmented volume. However, continuous supply of osteogenic signals appears to be required to compensate for adverse effects during polymer degradation.

A study on a tissue-engineered bone using rhBMP-2 induced periosteal cells with a porous nano-hydroxyapatite/collagen/poly(L-lactic acid) scaffold

We investigated the in vivo osteogenic ability of rhBMP-2 induced periosteal cells in a new porous scaffold, nano-hydroxyapatite (nano-HA)/collagen/poly(L-lactic acid) (PLA). The nano-HA/collagen/PLA composites were utilized as an extracellular matrix for a cell-based strategy of bone tissue engineering. Periosteal cells were cultivated with 500 ng ml(-1) rhBMP-2, followed by seeding into prewet nano-HA/collagen/PLA scaffolds. The cell-scaffold constructs were then subcutaneously implanted in nude mice compared to controls with cell suspension and scaffold alone. Scanning electron microscopy examination proved that the scaffold supported adhesion and proliferation of periosteal cells. Histological bone formation was observed only in experimental groups with cell transplants 8 weeks post-implantation. The animals of the control groups did not show bone formation. The results strongly encourage the approach of the transplantation of rhBMP-2 induced periosteal cells within a suitable carrier structure for bone regeneration.