Bioartificial Bone Grafts Research Articles

L-cysteine aided polyaniline capped SrO2 nanoceramics: Assessment of MC3T3-E1-arbitrated osteogenesis and anti-bactericidal efficacy on the polyurethane 2D nanofibrous substrate

Fabricating bioartificial bone graft ceramics retaining structural, mechanical, and bone induction properties akin to those of native stem-cell niches is a major challenge in the field of bone tissue engineering and regenerative medicine. Moreover, the developed materials are susceptible to microbial invasion leading to biomaterial-centered infections which might limit their clinical translation. Here, we successfully developed biomimetic porous scaffolds of polyurethane-reinforcedL-cysteine-anchored polyaniline capped strontium oxide nanoparticles to improve the scaffold’s biocompatibility, osteo-regeneration, mechanical, and antibacterial properties. The engineered nanocomposite substrate PU/L-Cyst-SrO2 @PANI (0.4 wt%) significantly promotes bone repair and regeneration by modulating osteolysis and osteogenesis. ALP activity, collagen-I, ARS staining, as well as biomineralization of MC3T3-E1 cells, were used to assess the biocompatibility and cytocompatibility of the developed scaffolds in vitro, confirming that the scaffold provided a favorable microenvironment with a prominent effect on cell growth, proliferation, and differentiation. Furthermore, osteogenic protein markers were studied using qRT-PCR with expression levels of runt-related transcription factor 2 (RUNX2), secreted phosphoprotein 1 (Spp-I), and collagen type I (Col-I). The overall results suggest that PU/L-Cyst-SrO2 @PANI (0.4 wt%) scaffolds showed superior interfacial biocompatibility, antibacterial properties, load-bearing ability, and osteoinductivity as compared to pristine PU. Thus, prepared bioactive nanocomposite scaffolds perform as a promising biomaterial substrate for bone tissue regeneration.

Tissue particularities and problems related to bone healing and fracture repair

Tissue particularities and problems related to bone healing and fracture repair

Clinical Application of 3-Dimensional Printing for Maxillofacial Reconstruction. A Review of Reported Cases

Well-established methods for reconstruction of maxillofacial bone defects include the use of autologous (non-) vascularized bone grafts. The drawbacks of these procedures are associated with donor site morbidity, intra-operative morbidity, and prolonged hospitalization (Shao et al., 2018; Maroulakos et al., 2019). Advances in the field of bone tissue engineering (BTE) over the past decades offer promising new treatment alternatives using biocompatible scaffold materials, autologous cells and growth factors. Combining BTE with recent advances in 3-dimensional (3D) printing technologies may soon allow manufacturing of large, bioartificial bone grafts with patient-specific architecture (Shao et al., 2018; Maroulakos et al., 2019). The aim of this study was to summarize the published cases, using 3D-printed devices and/or tissue engineered scaffolds to reconstruct bone defects of the jaws.

3D-SPA, a method to quantity the three dimensional static prosthetic alignment during conventional gait analysis

The aim of this pilot study was to determine, in a new experimental model, whether complex bioartificial monoblocs of relevant size and stability can be prefabricated in a defined three-dimensional design, in which the latissimus dorsi muscle serves as a natural bioreactor and the thoracodorsal vessel tree is prepared for axial construct perfusion. Eighteen sheep were included in the study, with six animals in each of three experimental groups. Vitalization of the β-tricalcium phosphate-based constructs was performed by direct application of unmodified osteogenic material from the iliac crest (group A), in vivo application of nucleated cell concentrate (NCC) from bone marrow aspirate (group B), and in vitro cultivation of bone marrow stromal cells (BMSC) in a perfusion bioreactor system (group C). The contours of the constructs were designed digitally and transferred onto the bioartificial bone grafts using a titanium cage, which was bent over a stereolithographic model of the defined subvolume intraoperatively. At the end of the prefabrication process, only the axial vascularized constructs of group A demonstrated vital bone formation with considerable stability. In groups B and C, the applied techniques were not able to induce ectopic bone formation. The presented computer-assisted workflow allows the prefabrication of custom-made bioartificial transplants.

Electrospun polycaprolactone/hydroxyapatite/ZnO nanofibers as potential biomaterials for bone tissue regeneration.

Fabricating a bioartificial bone graft possessing structural, mechanical and biological properties mimicking the real bone matrix is a major challenge in bone tissue engineering. Moreover, the developed materials are prone to microbial invasion leading to biomaterial centered infections which might limit their clinical translation. In the present study, biomimetic nanofibrous scaffolds of Poly ɛ-caprolactone (PCL)/nano-hydroxyapatite (nHA) were electrospun with 1wt%, 5wt%, 10wt%, 15wt% and 30wt% of zinc oxide (ZnO) nanoparticles in order to understand the optimal concentration range of (ZnO) nanoparticles balancing both biocompatibility and osteoregeneration. The developed nanofibrous scaffolds were successfully characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDAX), contact angle, fourier transform infrared spectroscopy (FTIR), wide-angle X-Ray diffraction (WAXD), brunaueremmett Teller (BET) surface area and tensile testing. Biocompatibility of the developed scaffolds at in vitro level was evaluated by culturing MG-63 cells and investigating the impact on cell viability, proliferation, protein adsorption, alkaline phosphatase (ALP) activity and biomineralization. The PCL/nHA scaffolds exhibited a 1.2-fold increase in cell viability and proliferation, while incorporation of ZnO nanoparticles to PCL/nHA imparted antimicrobial activity to the scaffolds with a progressive increase in the antimicrobial efficacy with increasing ZnO concentration. The results of cell viability were supported by ALP activity and mineralization assay, wherein, PCL/nHA/ZnO scaffolds showed higher ALP activity and better mineralization capacity as compared to pristine PCL. Although, the PCL/nHA/ZnO scaffolds with 10, 15 and 30wt% of ZnO particles exhibited superior antimicrobial efficacy against both gram-negative (E. coli) and gram-positive (S. aureus) bacteria, a significant decrease in the cell viability and mechanical properties was observed at higher concentrations of ZnO namely 15 and 30%. Amongst the various ZnO concentrations studied optimal cell viability, antimicrobial effect and mechanical strength were observed at 10wt.% ZnO concentration. Thus, the present study revealed that the biomimetic tri-component PCL/nHA/ZnO scaffolds with ZnO concentration range of ≤ 10% could be ideal for achieving optimal biocompatibility (cell proliferation, biomineralization, and antimicrobial capacity) and mechanical stability thus making it a promising biomaterial substrate for bone tissue regeneration.

In vivo tissue engineered bone versus autologous bone: stability and structure

This pilot study investigated the biomechanical properties of prefabricated, vascularized bioartificial bone grafts, which may provide an alternative bone source for the restoration of segmental osseous defects. Vascularized bioartificial bone grafts comprise an artificial customized scaffold made of beta-tricalcium phosphate. Bone formation along the prefabricated scaffold is induced by autogenous cancellous bone. Vascularization of the bone graft is provided by the host's vascular system. Within 6 months, a mammalian bioreactor (sheep were used in the present study) creates heterotopic vascularized bioartificial bone grafts of a predetermined anatomical shape, which can be harvested for reconstructing osseous defects. The bioartificial bone grafts in this study contained up to 25% bone tissue, as shown by histomorphometric analysis and computed tomography. Moreover, unconfined compression tests revealed that the constructs had mechanical characteristics similar to those of ovine cancellous bone. Therefore, this method could be applied to generate vascularized prefabricated bone substitutes for critical-size defects.

Bone Tissue Engineering Incorporating Poly(Propylene Fumarate) Composites: A Mini Review

Tissue engineering is intended to manipulate living cells to help develop substitutes for native tissues or remodel tissue. Bioartificial tissues are commonly explored in various tissue engineering ventures to overcome the disadvantages of working with native tissue. Poly(propylene fumarate) is a potential biomaterial for bioartificial bone grafts. The polymer’s many desirable physical and chemical properties have drawn significant research interest. This miniature review is intended to cover a small portion of the investigations of poly(propylene fumarate) as a bone tissue engineering biomaterial.

Prefabrication of vascularized facial bones

Critical size defects in the craniomaxillofacial region often result from ablative tumor surgery, inflammation and posttraumatic deformities. To date, autologous bone grafts are still the gold standard for the reconstruction of these defects; however, they are frequently associated with severe donor site morbidity as well as functional and aesthetic compromises. In this context various resorbable and non-resorbable bone replacement materials have been developed and intensively investigated. Particularly in critical size defects these materials fail due to their lack of osteogenic potential and endogenous vascularization. The combination of alloplastic osteoconductive scaffolds, osteogenic cells, and axial prevascularization in bioartificial bone grafts might present an innovative approach for the microsurgical reconstruction of critical size defects.

Engineering anatomically shaped vascularized bone grafts with hASCs and 3D-printed PCL scaffolds

The treatment of large craniomaxillofacial bone defects is clinically challenging due to the limited availability of transplantable autologous bone grafts and the complex geometry of the bones. The ability to regenerate new bone tissues that faithfully replicate the anatomy would revolutionize treatment options. Advances in the field of bone tissue engineering over the past few decades offer promising new treatment alternatives using biocompatible scaffold materials and autologous cells. This approach combined with recent advances in three-dimensional (3D) printing technologies may soon allow the generation of large, bioartificial bone grafts with custom, patient-specific architecture. In this study, we use a custom-built 3D printer to develop anatomically shaped polycaprolactone (PCL) scaffolds with varying internal porosities. These scaffolds are assessed for their ability to support induction of human adipose-derived stem cells (hASCs) to form vasculature and bone, two essential components of functional bone tissue. The development of functional tissues is assessed in vitro and in vivo. Finally, we demonstrate the ability to print large mandibular and maxillary bone scaffolds that replicate fine details extracted from patient's computed tomography scans. The findings of this study illustrate the capabilities and potential of 3D printed scaffolds to be used for engineering autologous, anatomically shaped, vascularized bone grafts.

En bloc prefabrication of vascularized bioartificial bone grafts in sheep and complete workflow for custom-made transplants

The aim of this pilot study was to determine, in a new experimental model, whether complex bioartificial monoblocs of relevant size and stability can be prefabricated in a defined three-dimensional design, in which the latissimus dorsi muscle serves as a natural bioreactor and the thoracodorsal vessel tree is prepared for axial construct perfusion. Eighteen sheep were included in the study, with six animals in each of three experimental groups. Vitalization of the β-tricalcium phosphate-based constructs was performed by direct application of unmodified osteogenic material from the iliac crest (group A), in vivo application of nucleated cell concentrate (NCC) from bone marrow aspirate (group B), and in vitro cultivation of bone marrow stromal cells (BMSC) in a perfusion bioreactor system (group C). The contours of the constructs were designed digitally and transferred onto the bioartificial bone grafts using a titanium cage, which was bent over a stereolithographic model of the defined subvolume intraoperatively. At the end of the prefabrication process, only the axial vascularized constructs of group A demonstrated vital bone formation with considerable stability. In groups B and C, the applied techniques were not able to induce ectopic bone formation. The presented computer-assisted workflow allows the prefabrication of custom-made bioartificial transplants.

Hyaluronan-based heparin-incorporated hydrogels for generation of axially vascularized bioartificial bone tissues: in vitro and in vivo evaluation in a PLDLLA–TCP–PCL-composite system

Smart matrices are required in bone tissue-engineered grafts that provide an optimal environment for cells and retain osteo-inductive factors for sustained biological activity. We hypothesized that a slow-degrading heparin-incorporated hyaluronan (HA) hydrogel can preserve BMP-2; while an arterio-venous (A-V) loop can support axial vascularization to provide nutrition for a bio-artificial bone graft. HA was evaluated for osteoblast growth and BMP-2 release. Porous PLDLLA-TCP-PCL scaffolds were produced by rapid prototyping technology and applied in vivo along with HA-hydrogel, loaded with either primary osteoblasts or BMP-2. A microsurgically created A-V loop was placed around the scaffold, encased in an isolation chamber in Lewis rats. HA-hydrogel supported growth of osteoblasts over 8 weeks and allowed sustained release of BMP-2 over 35 days. The A-V loop provided an angiogenic stimulus with the formation of vascularized tissue in the scaffolds. Bone-specific genes were detected by real time RT-PCR after 8 weeks. However, no significant amount of bone was observed histologically. The heterotopic isolation chamber in combination with absent biomechanical stimulation might explain the insufficient bone formation despite adequate expression of bone-related genes. Optimization of the interplay of osteogenic cells and osteo-inductive factors might eventually generate sufficient amounts of axially vascularized bone grafts for reconstructive surgery.

Simultaneous electrospin–electrosprayed biocomposite nanofibrous scaffolds for bone tissue regeneration

Currently, the application of nanotechnology in bone tissue regeneration is a challenge for the fabrication of novel bioartificial bone grafts. These nanostructures are capable of mimicking natural extracellular matrix with effective mineralization for successful regeneration of damaged tissues. The simultaneous electrospraying of nanohydroxyapatite (HA) on electrospun polymeric nanofibrous scaffolds might be more promising for bone tissue regeneration. In the current study, nanofibrous scaffolds of gelatin (Gel), Gel/HA (4:1 blend), Gel/HA (2:1 blend) and Gel/HA (electrospin-electrospray) were fabricated for this purpose. The morphology, chemical and mechanical stability of nanofibres were evaluated by means of field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy and with a universal tensile machine, respectively. The in vitro biocompatibility of different nanofibrous scaffolds was determined by culturing human foetal osteoblasts and investigating the proliferation, alkaline phosphatase (ALP) activity and mineralization of cells. The results of cell proliferation, ALP activity and FESEM studies revealed that the combination of electrospinning of gelatin and electrospraying of HA yielded biocomposite nanofibrous scaffolds with enhanced performances in terms of better cell proliferation, increased ALP activity and enhanced mineralization, making them potential substrates for bone tissue regeneration.

Prefabrication of vascularized bioartificial bone grafts in vivo for segmental mandibular reconstruction: experimental pilot study in sheep and first clinical application

The key elements for bioartificial bone formation in 3D matrices are large numbers of osteogenic cells and supplies of oxygen and nutrition. Vascularization becomes more important with the increasing size and complexity of seeded scaffolds required for clinical application in reconstructive craniomaxillofacial surgery. Prefabrication of vascularized bioartificial bone grafts in vivo might be an alternative to in vitro tissue engineering techniques. Two cylindrical beta-TCP-scaffolds (25 mm long) were intraoperatively filled with autogenous bone marrow from the iliac crest for cell loading and implanted into the latissimus dorsi muscle in 12 sheep. To determine the effect of axial perfusion, one scaffold in each sheep was surgically supplied with a central vascular bundle. Sheep were killed 3 months after surgery. Histomorphometric analysis showed autogenous bone marrow from the iliac crest was an effective source of osteogenic cells and growth factors, inducing considerable ectopic bone growth in all implanted scaffolds. Bone growth, ceramic resorption and angiogenesis increased significantly with axial perfusion. The results encourage the application of prefabricated bioartificial bone for segmental mandibular reconstruction in man. In clinical practice, vascularized bioartificial bone grafts could change the principles of bone transplantation with minimal donor site morbidity and no shape or volume limitations.

Electrospun nanostructured scaffolds for bone tissue engineering

The current challenge in bone tissue engineering is to fabricate a bioartificial bone graft mimicking the extracellular matrix (ECM) with effective bone mineralization, resulting in the regeneration of fractured or diseased bones. Biocomposite polymeric nanofibers containing nanohydroxyapatite (HA) fabricated by electrospinning could be promising scaffolds for bone tissue engineering. Nanofibrous scaffolds of poly- l-lactide (PLLA, 860 ± 110 nm), PLLA/HA (845 ± 140 nm) and PLLA/collagen/HA (310 ± 125 nm) were fabricated, and the morphology, chemical and mechanical characterization of the nanofibers were evaluated using scanning electron microscopy, Fourier transform infrared spectroscopy and tensile testing, respectively. The in vitro biocompatibility of different nanofibrous scaffolds was also assessed by growing human fetal osteoblasts (hFOB), and investigating the proliferation, alkaline phosphatase activity (ALP) and mineralization of cells on different nanofibrous scaffolds. Osteoblasts were found to adhere and grow actively on PLLA/collagen/HA nanofibers with enhanced mineral deposition of 57% higher than the PLLA/HA nanofibers. The synergistic effect of the presence of an ECM protein, collagen and HA in PLLA/collagen/HA nanofibers provided cell recognition sites together with apatite for cell proliferation and osteoconduction necessary for mineralization and bone formation. The results of our study showed that the biocomposite PLLA/collagen/HA nanofibrous scaffold could be a potential substrate for the proliferation and mineralization of osteoblasts, enhancing bone regeneration.

Prefabrication of vascularised bioartificial bone grafts in vivo—experimental pilot study in sheep and first clinical application

Prefabrication of vascularised bioartificial bone grafts in vivo—experimental pilot study in sheep and first clinical application

Bioartificial bone grafting:Tarsal joint fusion in a dog using a bioartificial composite bone graft consisting of β-tricalciumphosphate and platelet rich plasma – A case report

Grafting of large bone defects caused by trauma or tumor resection still remains a problem to solve. In experimental studies as well as in human dentistry, osteoconduction and biodegradation of the beta-tricalciumphosphate Cerasorb as well as osteoinductive capabilities of platelet rich plasma have been proven. In case of luxation of the right tarsal joint, including a compressive fracture of the forth tarsal bone, the recommended use of autologous cancellous bone to support osseous fusion was replaced by the use of a bioartificial bone graft. Biodegradation of the bone graft was proven clinically and radiographically. Complete osseous fusion of the intertarsal joint occurred. The use of the beta-tricalciumphosphate Cerasorb in combination with platelet rich plasma to support a partial arthrodesis of the tarsal joint in a dog did not impede the healing process but led to full recovery of the patient, indicating that this concept of bioartificial bone grafting could support bone healing.

Bone and soft tissue regeneration by bone marrow mesenchymal cells

Culture of bone marrow blood produces bone marrow mesenchymal cells that adhere to the bottom of the culture dish. These cells are known to include cells that can differentiate in various directions. Culturing these marrow mesenchymal cells with differentiation factors and biomaterials can achieve regeneration of bone and soft tissue. The present study showed that culture of marrow mesenchymal cells with porous artificial bone material in an osteogenic culture medium containing dexamethasone could produce new bone tissue on the artificial material. This bio-artificial bone graft substitute could effectively regenerate bone tissue when it was implanted in vivo. Porous artificial bone material treated with a small amount of bone morphogenetic protein (BMP) and perfused with marrow mesenchymal cells also markedly stimulated bone regeneration by the interaction between the cells and BMP. Similarly, when an artificial dermis made of collagen sponge was perfused with marrow mesenchymal cells and used to cover a skin defect, the regeneration of blood vessels was stimulated. Since the present results demonstrated the ability of marrow mesenchymal cells to regenerate bone and soft tissue, these cells are expected to be useful for tissue regeneration therapy.