Skull Regeneration Research Articles

Facile design of biofunctionalized nanocomposite hydrogel to potentiate angiogenesis and osteogenesis for the skull regeneration

The clinical treatment of cranial defect reconstruction using hydrogels faces challenges such as inadequate biomechanical strength and limited biofunctional effects. In this study, we have addressed these issues by developing a novel hydrogel. This hydrogel composes desferrioxamine-modified laponite nanoplatelets (LAP/DFO) combined with tannin-modified poly(vinyl alcohol) (PVA/TA), aiming to closely emulate the natural organic-inorganic bony matrix. Our results indicated that the multifunctional hydrogel system, particularly when incorporating LAP/DFO (referred to as PL10), could form a highly ordered porous structure, achieve appropriate biomechanical strength, and release bioactive factors as expected. This system enhanced the adhesion and proliferation of human umbilical vein endothelial cells (HUVECs) for angiogenesis and promoted mesenchymal stem cells (MSCs) osteogenic differentiation for osteogenesis in vitro. Moreover, in vivo investigations confirmed the efficacy of the multifunctional hydrogels, particularly PL10, in enhancing bone regeneration compared to blank PVA. Collectively, this study contributes valuable insights into the design of bioactive factor delivery systems and offers efficient therapeutic strategies for promoting the repair of cranial defects.

A robust and biodegradable hydroxyapatite/poly(lactide-co-ε-caprolactone) electrospun membrane for dura repair.

Typically occurring after trauma or neurosurgery treatments, dura mater defect and the ensuing cerebrospinal fluid (CSF) leakage could lead to a number of serious complications and even patient's death. Although numerous natural and synthetic dura mater substitutes have been reported, none of them have been able to fulfill the essential properties, such as anti-adhesion, leakage blockage, and pro-dura rebuilding. In this study, we devised and prepared a series of robust and biodegradable hydroxyapatite/poly(lactide-co-ε-caprolactone) (nHA/PLCL) membranes for dura repair via an electrospinning technique. In particular, PLLA/PCL (80/20) was selected for electrospinning due to its mechanical properties that most closely resembled natural dural tissue. Studies by SEM, XRD, water contact angle and in vitro degradation showed that the introduction of nHA would destroy PLCL's crystalline structure, which would further affect the mechanical properties of the nHA/PLCL membranes. When the amount of nHA added increased, so did the wettability and in vitro degradation rate, which accelerated the release of nHA. In addition, the high biocompatibility of nHA/PLCL membranes was demonstrated by in vitro cytotoxicity data. The in vivo rabbit dura repair model results showed that nHA/PLCL membranes provided a strong physical barrier to stop tissue adhesion at dura defects. Meanwhile, the nHA/PLCL and commercial group's CSF had a significantly lower number of inflammatory cells than the control groups, validating the nHA/PLCL's ability to effectively lower the risk of intracranial infection. Findings from H&E and Masson-trichrome staining verified that the nHA/PLCL electrospun membrane was more favorable for fostering dural defect repair and skull regeneration. Moreover, the relative molecular weight of PLCL declined dramatically after 3 months of implantation, according to the results of the in vivo degradation test, but it retained the fiber network structure and promoted tissue growth, demonstrating the good stability of the nHA/PLCL membranes. Collectively, the nHA/PLCL electrospun membrane presents itself as a viable option for dura repair.

A Novel 3D‐Printed Bi‐Layer Cranial‐Brain Patch Promotes Brain Injury Repair and Bone Tissue Regeneration

AbstractTraumatic brain injury (TBI), recognized as the world's most serious public health problem, currently lacks effective treatment options. The development of the patch has great clinical significance whether it is used as a skull implant material or TBI repair. In response to this critical health challenge, a novel 3D‐printed bi‐layer cranial‐brain patch (SMB6) with dual functionality, addressing both TBI repair and skull regeneration, is developed. In the first layer, the incorporation of high concentrations of mesoporous bioactive glass nanoparticles establishes a microenvironment for bone regeneration. Meanwhile, the second layer, comprised of methacrylated silk fibroin hydrogel, provides essential mechanical support for nanocell membrane vesicles loaded with macrophage colony‐stimulating factor and interleukin‐6. This innovative design aims to interrupt the cascade of secondary brain injury. In experimental models of TBI, SMB6 demonstrates remarkable efficacy in inhibiting brain edema, exerting therapeutic effects on blood vessels, nerves, and inflammation. Additionally, promising outcomes are observed in promoting bone regeneration in skull defect models. This work not only introduces a potential therapeutic patch for TBI‐related diseases but also provides novel insights for the clinical translation of cranial patches.

Immunoregulation in Skull Defect Repair with a Smart Hydrogel Loaded with Mesoporous Bioactive Glasses.

Skull defect repair is a complex and critical medical challenge, and there is an urgent need to develop multifunctional tissue engineering scaffolds for skull regeneration. The success of bone tissue engineering depends on the construction of scaffolds that can regulate the immune microenvironment of bone regeneration and mimic the liquid crystal and viscoelastic properties of natural bone extracellular matrix. Hence, a smart hydrogel (PEGDA5/AM15/CLC-BMP-4@MBG) with good biocompatibility and the ability to modulate the wound immune microenvironment has been developed for the repair of skull defects. The hydrogel consists of chitin liquid crystal hydrogel (PEGDA5/AM15/CLC) and mesoporous bioactive glasses (MBGs) loaded with bone morphogenetic protein-4 (BMP-4). The liquid crystal hydrogel not only offers the necessary biological support and mechanical properties but also maintains the stability of the liquid crystal state, facilitating adhesion and regeneration of surrounding bone tissue. In addition, BMP-4@MBG intelligently regulates the release rate of BMP-4 in response to changes in wound microenvironment, thus effectively promoting the transformation of macrophages from M1 to M2 macrophages. At the same time, Ca2+ and Si4+ released by MBG degradation and BMP-4 synergically promote bone repair process. The PEGDA5/AM15/CLC-BMP-4@MBG hydrogel shows excellent immunomodulatory and osteogenic properties of bone microenvironment and is a promising scaffold material for bone tissue engineering.

Inverse design of skull osteoinductive implants with multi-level pore structures through machine learning.

How to accurately design a personalized matching implant that can induce skull regeneration is the focus of current research. However, the design space for the porous structure of implants is extensive, and the mapping relationships between these structures and their mechanical and osteogenic properties are complex. At present, the forward design of skull implants mainly relies on expert experience, leading to high cost and a lengthy process, while the existing inverse design approaches face challenges due to data dependence and manufacturing process errors. This study presents an efficient inverse design method for personalized multilevel structures of skull implants using a machine learning pipeline composed of a finite element method, topological optimization, and neural networks. Based on the mechanical response of the human body falls, this method can tailor multi-level structures for implants in various defect positions. The results show that the proposed method establishes a bidirectional relationship between topological parameters and mechanical properties, enabling the customization of mechanical behavior at low computational cost while accounting for manufacturing errors in the 3D printing process. Additionally, the design results are also mutually consistent with analytical relationships between lattice parameters and the elastic modulus obtained from experiments and finite element simulations. Thus, this study provides a general and practical approach to rapidly design skull osteoinductive implants.

Polysaccharide-Based Composite Hydrogel with Hierarchical Microstructure for Enhanced Vascularization and Skull Regeneration.

Critical-size skull defects caused by trauma, infection, and tumor resection raise great demands for efficient bone substitutes. Herein, a hybrid cross-linked hierarchical microporous hydrogel scaffold (PHCLS) was successfully assembled by a multistep procedure, which involved (i) the preparation of poly(lactic-co-glycolic)/nanohydroxyapatite (PLGA-HAP) porous microspheres, (ii) embedding the spheres in a solution of dopamine-modified hyaluronic acid and collagen I (Col I) and cross-linking via dopamine polyphenols binding to (i) Col I amino groups (via Michael addition) and (ii) PLGA-HAP (via calcium ion chelation). The introduction of PLGA-HAP not only improved the diversity of pore size and pore communication inside the matrix but also greatly enhanced the compressive strength (5.24-fold, 77.5 kPa) and degradation properties to construct a more stable mechanical structure. In particular, the PHCLS (200 mg, nHAP) promoted the proliferation, infiltration, and angiogenic differentiation of bone marrow mesenchymal stem cells in vitro, as well as significant ectopic angiogenesis and mineralization with a storage modulus enhancement of 2.5-fold after 30 days. Meanwhile, the appropriate matrix microenvironment initiated angiogenesis and early osteogenesis by accelerating endogenous stem cell recruitment in situ. Together, the PHCLS allowed substantial skull reconstruction in the rabbit cranial defect model, achieving 85.2% breaking load strength and 84.5% bone volume fractions in comparison to the natural cranium, 12 weeks after implantation. Overall, this study reveals that the hierarchical microporous hydrogel scaffold provides a promising strategy for skull defect treatment.

3D‐printed degradable hydroxyapatite bioactive ceramics for skull regeneration

AbstractHydroxyapatite (HA) bioceramics have been extensively employed as bone tissue scaffolds owing to their biodegradability and osteoinductivity. In our work, HA, a significant component of natural bone tissue used as the raw material to produce porous scaffolds employing three‐dimensional (3D)‐printing technology. Physical and chemical properties, porosity, and compression resistance of the scaffolds were investigated in vitro. The scaffold was confirmed to have a large number of interconnected pore structures on the surface and inside HA scaffolds showed good cell compatibility and cell adhesion in cell text. To analyze the effect of the scaffold on bone repair and regeneration in vivo, the large‐size defect of beagle skull was repaired with a 3D printing group and an autologous bone group (ABG) for 8 months. Images and histological analysis of the 3D printing group indicated better integration with adjacent tissues. However, there were obvious gaps in the ABG, which indicates weak bone regeneration ability of this group due to unmatched implant dimension. Immunohistochemistry and immunofluorescence results showed that 3D‐printed scaffolds had a highly vascularized structure. This study indicates that 3D‐printed bioceramics scaffolds that are osteoinductivity and biodegradable have great potential in maxillofacial bone regeneration.

Modulating Temporospatial Phosphate Equilibrium by Nanoparticulate Mineralized Collagen Materials Induces Osteogenesis via PiT-1 and PiT-2.

The temporospatial equilibrium of phosphate contributes to physiological bone development and fracture healing, yet optimal control of phosphate content has not been explored in skeletal regenerative materials. Nanoparticulate mineralized collagen glycosaminoglycan (MC-GAG) is a synthetic, tunable material that promotes in vivo skull regeneration. In this work, the effects of MC-GAG phosphate content on the surrounding microenvironment and osteoprogenitor differentiation are investigated. This study finds that MC-GAG exhibits a temporal relationship with soluble phosphate with elution early in culture shifting to absorption with or without differentiating primary bone marrow-derived human mesenchymal stem cells (hMSCs). The intrinsic phosphate content of MC-GAG is sufficient to stimulate osteogenic differentiation of hMSCs in basal growth media without the addition of exogenous phosphate in a manner that can be severely reduced, but not eliminated, by knockdown of the sodium phosphate transporters PiT-1 or PiT-2. The contributions of PiT-1 and PiT-2 to MC-GAG-mediated osteogenesis are nonredundant but also nonadditive, suggestive that the heterodimeric form is essential to its activity. These findings indicate that the mineral content of MC-GAG alters phosphate concentrations within a local microenvironment resulting in osteogenic differentiation of progenitor cells via both PiT-1 and PiT-2.

Osteoprotegerin-eluting nanoparticulate mineralized collagen scaffolds improve skull regeneration

Custom synthesis of extracellular matrix (ECM)-inspired materials for condition-specific reconstruction has emerged as a potentially translatable regenerative strategy. In skull defect reconstruction, nanoparticulate mineralized collagen glycosaminoglycan scaffolds (MC-GAG) have demonstrated osteogenic and anti-osteoclastogenic properties, culminating in the ability to partially heal in vivo skull defects without the addition of exogenous growth factors or progenitor cell loading. In an effort to reduce catabolism during early skull regeneration, we fabricated a composite material (MCGO) of MC-GAG and recombinant osteoprotegerin (OPG), an endogenous anti-osteoclastogenic decoy receptor. In the presence of differentiating osteoprogenitors, MCGO demonstrated an additive effect with endogenous OPG limited to the first 14 days of culture with total eluted and scaffold-bound OPG exceeding that of MC-GAG. Functionally, MCGO exhibited similar osteogenic properties as MC-GAG, however, MCGO significantly reduced maturation and resorptive activities of primary human osteoclasts. In a rabbit skull defect model, MCGO scaffold-reconstructed defects displayed higher mineralization as well as increased hardness and microfracture resistance compared to non-OPG functionalized MC-GAG scaffolds. The current work suggests that MCGO is a development in the goal of reaching a materials-based strategy for skull regeneration.

Porous gelatin microsphere-based scaffolds containing MC3T3-E1 cells and calcitriol for the repair of skull defect

There is an increasing demand for biomaterials with skull regeneration for clinical application. However, most of the current skull repair materials still have limitations, such as inadequate sources, poor cell adherence, differentiation, tissue infiltration, and foreign body sensation. Therefore, this study developed porous microsphere-based scaffolds containing mouse embryonic osteoblast precursor cells (MC3T3-E1 cells) and calcitriol (Cal) using gelatin and gelatin/hydroxyapatite through green freeze-crosslinking and freeze-drying. Gelatin was employed to prepare porous microspheres with a particle size of 100-300μm, containing open pores of 2-70μm and interconnected paths. Furthermore, the addition of Cal to porous gelatin microsphere-based scaffolds containing MC3T3-E1 cells (PGMSs-MC) and porous gelatin/hydroxyapatite composite microspheres containing MC3T3-E1 cells (HPGMSs-MC) improved their osteoinductivity and cell proliferation and promoted the formation of mature and well-organized bone. The developed Cal-HPGMSs-MC and Cal-PGMSs-MC displayed a good porous structure and cytocompatibility, histocompatibility, osteoconductivity, and osteoinduction. Thus, the designed scaffolds provide a promising prospect for tissue-engineered constructs with skull growth and integration, laying a foundation for further research on the reconstruction of skull defects.

An instantly fixable and self-adaptive scaffold for skull regeneration by autologous stem cell recruitment and angiogenesis.

Limited stem cells, poor stretchability and mismatched interface fusion have plagued the reconstruction of cranial defects by cell-free scaffolds. Here, we designed an instantly fixable and self-adaptive scaffold by dopamine-modified hyaluronic acid chelating Ca2+ of the microhydroxyapatite surface and bonding type I collagen to highly simulate the natural bony matrix. It presents a good mechanical match and interface integration by appropriate calcium chelation, and responds to external stress by flexible deformation. Meanwhile, the appropriate matrix microenvironment regulates macrophage M2 polarization and recruits endogenous stem cells. This scaffold promotes the proliferation and osteogenic differentiation of BMSCs in vitro, as well as significant ectopic mineralization and angiogenesis. Transcriptome analysis confirmed the upregulation of relevant genes and signalling pathways was associated with M2 macrophage activation, endogenous stem cell recruitment, angiogenesis and osteogenesis. Together, the scaffold realized 97 and 72% bone cover areas after 12 weeks in cranial defect models of rabbit (Φ = 9 mm) and beagle dog (Φ = 15 mm), respectively.

Near-infrared light control of GelMA/PMMA/PDA hydrogel with mild photothermal therapy for skull regeneration

The development of bone tissue engineering indicates some new paths for bone defect repair. Mild photothermal therapy (PTT) is flourishing as an exciting potential method for bone regeneration. Polydopamine nanoparticles exhibit good absorption at infrared wavelengths and can be used as a viable option for the application of mild PTT to bone defects. Herein, a gelatin-methacryloyl/poly(methyl methacrylate)/polydopamine (GelMA/PMMA/PDA) hydrogel was formulated and assessed in terms of mechanical and biological features. We observed that the addition of methacryloyl groups into gelatin and the introduction of PMMA improved the mechanical properties of the hydrogel and ensure the biosecurity. The GelMA/PMMA/PDA hydrogel demonstrated favorable photothermal ability, biocompatibility, and osteogenic effect. In the rat skull defect model, the GelMA/PMMA/PDA hydrogel with mild PTT possesses better bone repair compared with hydrogel-only and control groups. Thus, this mild photothermal hydrogel platform has a beneficial osteogenic ability and provides a novel approach to treat bone defects.

Enhanced Bone Regeneration Using a ZIF-8-Loaded Fibrin Composite Scaffold.

In the present study, fibrin-based biomaterials made of zeolite imidazole framework-8 (ZIF-8) and fibrin gel (Z-FG) are fabricated with the aim of enhancing skull regeneration. X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet (UV)-vis spectrophotometry, Fourier transform infrared spectroscopy, and rheometry are used to characterize ZIF-8 and Z-FG. The influences of ZIF-8 on the physical properties of fibrin gel (e.g., porosity, modulus, and in vitro biodegradation) are investigated, and the effect of ZIF-8 concentration on fibrin gel properties in vitro is determined by seeding ectomesenchymal stem cells (EMSCs) over Z-FG. EMSC osteogenic differentiation reveals higher expression of bone-related proteins and higher calcium deposition and alkaline phosphatase activity, indicating that Z-FG may be a good osteoinductive biomaterial. Furthermore, these results show that the piezochannel and yes-associated protein (YAP) signaling pathway are involved in the differentiation process. In addition, the in vivo results demonstrate that Z-FG increases bone formation in critical-sized calvarial defects in rats. Thus, the developed composite scaffold may be a suitable biomaterial for skull tissue-engineering applications.

β-Catenin Limits Osteogenesis on Regenerative Materials in a Stiffness-Dependent Manner.

Targeted refinement of regenerative materials requires mechanistic understanding of cell-material interactions. The nanoparticulate mineralized collagen glycosaminoglycan (MC-GAG) scaffold is shown to promote skull regeneration in vivo without additive exogenous growth factors or progenitor cells, suggesting potential for clinical translation. This work evaluates modulation of MC-GAG stiffness on canonical Wnt (cWnt) signaling. Primary human bone marrow-derived mesenchymal stem cells (hMSCs) are differentiated on two MC-GAG scaffolds (noncrosslinked, NX-MC, 0.3kPa vs conventionally crosslinked, MC, 3.9kPa). hMSCs increase expression of activated β-catenin, the major cWnt intracellular mediator, and the mechanosensitive YAP protein with near complete subcellular colocalization on stiffer MC scaffolds. Overall Wnt pathway inhibition reduces activated β-catenin and osteogenic differentiation, while elevating BMP4 and phosphorylated Smad1/5 (p-Smad1/5) expression on MC, but not NX-MC. Unlike Wnt pathway downregulation, isolated canonical Wnt inhibition with β-catenin knockdown increases osteogenic differentiation and mineralization specifically on the stiffer MC. β-catenin knockdown also increases p-Smad1/5, Runx2, and BMP4 expression only on the stiffer MC material. Thus, while stiffness-induced activation of the Wnt and mechanotransduction pathways promotes osteogenesis on MC-GAG, activated β-catenin is a limiting agent and may serve as a useful target or readout for optimal modulation of stiffness in skeletal regenerative materials.

Cyclic Adenosine Monophosphate-Enhanced Calvarial Regeneration by Bone Marrow-Derived Mesenchymal Stem Cells on a Hydroxyapatite/Gelatin Scaffold.

Cyclic adenosine monophosphate (cAMP) plays a significant role in inducing new bone formation by mediating various signal pathways. However, cAMP, combined with biomaterials, is rarely investigated to reconstruct calvarial defects. In this study, cAMP was loaded into a hydroxyapatite (HA)/gelatin (Gel) construct and implanted into critical skull defects in rats to evaluate the potential for enhancing skull regeneration. The physiochemical characteristics, the biocompatibility of Gel and HA/Gel scaffolds, and the regenerated bone tissue were assessed. The resulting HA/Gel scaffolds possessed a 3D interconnected porous structure with extensively distributed HA crystals and favorable physiochemical properties. Rat bone marrow-derived mesenchymal stem cells (rBMSCs) within the HA/Gel scaffold showed greater biocompatibility. Compared with the Gel and HA/Gel groups, the cAMP-HA/Gel group revealed the highest bone density, more mature mineralized tissue, and more favorable integration between the new bone and inherent bone as analyzed by cone beam computed tomography and hematoxylin & eosin and Masson staining, respectively. Collectively, our study verified HA/Gel scaffolds as a prospective biomimetic treatment with biocompatibility and the therapeutic potential of cAMP in promoting new bone growth of a skull, which indicates its promise as a growth factor for bone tissue engineering.

The latest study on biomimetic mineralized collagen-based bone materials for pediatric skull regeneration and repair

As a worldwide challenge in the field of neurosurgery, there is no effective treatment method for pediatric skull defects repair in clinic. Currently clinical used cranioplasty materials couldn't undergo adjustment in response to skull growth and deformation. An ideal material for pediatric cranioplasty should fulfill the requirements of achieving complete closure, good osseointegration, biodegradability and conformability, sufficient cerebral protection and optimal aesthetic, and functional restoration of calvaria. Biomimetic mineralized collagen-based bone material is a kind of material that simulates the microstructural unit of natural bone on the nanometer scale. Because of its high osteogenic activity, it is widely used in repair of all kinds of bone defects. Recently, the biomimetic mineralized collagen-based bone materials have successfully been applied for cranial regeneration and repair with satisfactory results. This review mainly introduces the characteristics of the biomimetic mineralized collagen-based bone materials, the advantages for the repair of pediatric skull defects, and the related progresses.

Halloysites modified polyethylene glycol diacrylate/thiolated chitosan double network hydrogel combined with BMP-2 for rat skull regeneration

Hydrogel serve as bone tissue engineering have lately received great attention for their good biocompatibility and structures similar to natural extracellular matrices. However, a single component polymer hydrogel is generally detrimental to cell adhesion due to the weaker mechanical properties, which limits their application considerably. In an effort to overcome this disadvantage, we adopt an unconventional dual network hydrogels consisting of the polyethylene glycol diacrylate (PEGDA) covalent network, a thiolated chitosan (TCS) ion crosslinking network and thiolated halloysites (T-HNTs) as reinforcing filler. In addition, bone morphogenetic protein-2 (BMP-2) was loaded into the prepared dual network (DN) hydrogel to improve the bone regeneration function of the DN hydrogel. The resulting PEGDA/TCS/T-HNTs hydrogels showed favourable mechanical property, higher crosslinking density, the lower swelling degree, excellent biocompatibility and cell adhesion ability. The histomorphometric and immunohistochemical analyses revealed the excellent bone regeneration ability for composite hydrogel after implant into rat skull defect. Thus, our results indicated that composite scaffold can be applied as a new bone regeneration biomaterial to be applied as a local drug delivery system with good bone induction performance.

Stiffness of Nanoparticulate Mineralized Collagen Scaffolds Triggers Osteogenesis via Mechanotransduction and Canonical Wnt Signaling.

The ability of the extracellular matrix (ECM) to instruct progenitor cell differentiation has generated excitement for the development of materials-based regenerative solutions. Described a nanoparticulate mineralized collagen glycosaminoglycan (MC-GAG) material capable of inducing in vivo skull regeneration without exogenous growth factors or ex vivo progenitor cell-priming is described previously. Here, the contribution of titrating stiffness to osteogenicity is evaluated by comparing noncrosslinked (NX-MC) and crosslinked (MC) forms of MC-GAG. While both materials are osteogenic, MC demonstrates an increased expression of osteogenic markers and mineralization compared to NX-MC. Both materials are capable of autogenously activating the canonical BMPR signaling pathway with phosphorylation of Smad1/5. However, unlike NX-MC, human mesenchymal stem cells cultured on MC demonstrate significant elevations in the major mechanotransduction mediators YAP and TAZ expression, coincident with β-catenin activation in the canonical Wnt signaling pathway. Inhibition of YAP/TAZ activation reduces osteogenic expression, mineralization, and β-catenin activation in MC, with less of an effect on NX-MC. YAP/TAZ inhibition also results in a reciprocal increase in Smad1/5 phosphorylation and BMP2 expression. The results indicate that increasing MC-GAG stiffness induces osteogenic differentiation via the mechanotransduction mediators YAP/TAZ and the canonical Wnt signaling pathway, whereas the canonical BMPR signaling pathway is activated independent of stiffness.

Effect of Honeycomb β-TCP Geometrical Structure on Bone Tissue Regeneration in Skull Defect.

The effect of the geometric structure of artificial biomaterials on skull regeneration remains unclear. In a previous study, we succeeded in developing honeycomb β-tricalcium phosphate (β-TCP), which has through-and-through holes and is able to provide the optimum bone microenvironment for bone tissue regeneration. We demonstrated that β-TCP with 300-μm hole diameters induced vigorous bone formation. In the present study, we investigated how differences in hole directions of honeycomb β-TCP (horizontal or vertical holes) influence bone tissue regeneration in skull defects. Honeycomb β-TCP with vertical and horizontal holes was loaded with BMP-2 using Matrigel and Collagen gel as carriers, and transplanted into skull bone defect model rats. The results showed that in each four groups (Collagen alone group, Matrigel alone group, Collagen + BMP group and Matrigel + BMP-2), vigorous bone formation was observed on the vertical β-TCP compared with horizontal β-TCP. The osteogenic area was larger in the Matrigel groups (with and without BMP-2) than in the Collagen group (with and without BMP-2) in both vertical β-TCP and horizontal β-TCP. However, when BMP-2 was added, the bone formation area was not significantly different between the Collagen group and the Matrigel group in the vertical β-TCP. Histological finding showed that, in vertical honeycomb β-TCP, new bone formation extended to the upper part of the holes and was observed from the dura side to the periosteum side as added to the inner walls of the holes. Therefore, we can control efficient bone formation by creating a bone microenvironment provided by vertical honeycomb β-TCP. Vertical honeycomb β-TCP has the potential to be an excellent biomaterial for bone tissue regeneration in skull defects and is expected to have clinical applications.

<i>In Vivo</i> Clinical Trial of Porous Starch-Hydroxyapatite Composite Biomaterials for Bone Regeneration

Biodegradable scaffold is an accepted and commercialized medical alternative choice for bone regeneration. In this project, we used our new invention, porous starch-Hydroxyapatite (HA) composite for in vivo clinical trial. The products were prepared from medical grade Thai rice starch mixed with high purity (>97%) HA powder from fresh cow bone, and already passed in vivo animal biocompatibility test, then processed by freeze-drying. There were 44 volunteers from orthopedic and neurosurgical division, 4 and 40 patients, respectively. The results were assessed by operative surgeons and nurses, pre-and intraoperative period, including size appropriateness, comfort handle, ease of cutting, void space filling, water stability, product weight, shelf storage, package opening, contamination risk and waste removal. All average satisfactory scales were more than 95% rating. For postoperative period, at least 6 months, the soft tissue swellings around surgical areas were resoluted about 3 days as usual healing process. There were no any symptoms or signs of infection or allergic reactions. The follow up of x-ray imaging showed well ossification about 2 months. All patients have gained good functional performance. So porous starch-HA composites biomaterial can be used for human bone and skull regeneration with completely safety and efficacy.