Regeneration Of Critical Bone Defects Research Articles

Mild Thermotherapy-Assisted GelMA/HA/MPDA@Roxadustat 3D-Printed Scaffolds with Combined Angiogenesis-Osteogenesis Functions for Bone Regeneration.

Early reconstruction of the vascular network is a prerequisite to the effective treatment of substantial bone defects. Traditional 3D printed tissue engineering scaffolds designed to repair large bone defects do not effectively regenerate the vascular network, and rely only on the porous structure within the scaffold for nutrient transfer and metabolic waste removal. This leads to delayed bone restoration and hence functional recovery. Therefore, strategies for generation scaffolds with the capacity to efficiently regenerate vascularization should be developed. This study loads roxarestat (RD), which can stabilize HIF-1α expression in a normoxic environment, onto the mesopore polydopamine nanoparticles (MPDA@RD) to enhance the reconstruction of vascular network in large bone defects. Subsequently, MPDA@RD is mixed with GelMA/HA hydrogel bioink to fabricate a multifunctional hydrogel scaffold (GHM@RD) through 3D printing. In vitro results show that the GHM@RD scaffolds achieve good angiogenic-osteogenic coupling by activating the PI3K/AKT/HSP90 pathway in BMSCs and the PI3K/AKT/HIF-1α pathway in HUVECs under mild thermotherapy. In vivo experiments reveal that RD and mild hyperthermia synergistically induce early vascularization and bone regeneration of critical bone defects. In conclusion, the designed GHM@RD drug delivery scaffold with mild hyperthermia holds great therapeutic value for future treatment of large bone defects.

Bioinspired Bone Seed 3D‐Printed Scaffold via Trapping Black Phosphorus Nanosheet for Bone Regeneration

Significance of endogenous mineralization in bone reconstruction is paramount, as it facilitates the accumulation of calcium ions for bone tissue deposition. However, conventional 3D‐printed scaffolds lack the capacity for calcium ion enrichment and mineralization, coupled with their low bone inductive activity. Inspired from the development of natural plant seeds, a biomimetic 3D printing scaffold is developed by implanting photosensitive black phosphorus “bone seeds” (BS), guiding a sequential process mirroring rooting (osteoblast recruitment), sprouting (fibrous callus mineralization), flowering (osseous callus formation), and fruiting (callus plasticity). BS were trapped onto porous 3D polycaprolactone (PCL) scaffolds with aminated surfaces via electrostatic interactions between phosphates and amino groups, creating the PCL‐BS scaffold that can actively capture calcium ions for accelerating the endogenous regeneration of critical bone defects. In vitro and in vivo experiments show that the PCL‐BS scaffold has good biocompatibility and strong osteogenic ability for rapid new bone regeneration under near‐infrared (NIR) stimulation. In addition, whole transcriptome sequencing analysis is performed to reveal the transcriptomic mechanism of BS involved in signal transduction and network regulation during bone regeneration. This NIR light‐regulated biomimetic BS inspired by seed planting, introduces a pioneering concept in the design of 3D printing bone repair scaffolds.

Critical-size defects reconstruction with four different bone grafts associated with e-PTFE membrane: Ahistomorphometric experimental invivo study.

The goal of this study was to assess the newly formed bone and the remnant biomaterial by comparing four different bone grafts used to treat critical-size defects, associated or not with the non-resorbable membrane. Two calvaria critical-size bone defects were created in 50 male Wistar rats. They were divided into blood (G1), autogenous (G2), bioglass (G3), hydroxyapatite (G4), and xenograft (G5) groups, associated or not with e-PTFE. The experimental periods were 15 and 45 days. Sections were prepared for histomorphometric assessment. All data were analyzed by the mixed-effects model with multiple comparisons (significance level, p < .05). A similar level of new bone was observed for all groups, associated with a high level of vascularization. G1 and G2 ensured sovereignty over the greater quantity of new bone. A non-significant result was reported comparing groups with and without membranes. No significant result was found between the experimental synthetic biomaterials (G3 and G4). G5L achieved 22.0% of new bone after 45 days (p > .05). All groups had a stable volume of biomaterial kept in the short term (p > .05). G2 was the best material for new bone formation and final volume of biomaterial, followed by G4 < G5 < G3. Thus, it is possible that G4 had a better degradation profile among the experimental groups. The best results were found in the autogenous group, with higher resorption and integration; non-significative new bone was found among the experimental groups; and the regeneration of critical bone defects using an e-PTFE barrier did not present significant results on new bone formation.

Assessment of rhBMP-2-loaded bovine hydroxyapatite granules in the guided bone regeneration of critical bone defect in rat mandible bone

Assessment of rhBMP-2-loaded bovine hydroxyapatite granules in the guided bone regeneration of critical bone defect in rat mandible bone

Comparison of rhBMP-2 in Combination with Different Biomaterials for Regeneration in Rat Calvaria Critical-Size Defects.

Regeneration of critical bone defects requires the use of biomaterials. The incorporation of osteoinductive agents, such as bone morphogenetic proteins (BMPs), improves bone formation. This study aimed to compare the efficacy of rhBMP-2 in combination with different materials for bone regeneration in critical-sized rat calvarial defects. This was an experimental animal study using 30 rats. In each rat, two 5-mm critical-size defects were made in the calvaria (60 bone defects in total) using a trephine. All rats were randomized to one of the six groups: control (C), autograft + rhBMP-2 (A), absorbable collagen sponge + rhBMP-2 (ACS), β-tricalcium phosphate + rhBMP-2 (B-TCP), bovine xenograft + rhBMP-2 (B), and hydroxyapatite + rhBMP-2 (HA). The outcome was assessed after 4 and 8 weeks using histological description and the histological bone healing scale. Statistical analysis was performed using the Kruskal-Wallis and Mann–Whitney U tests, with a p-value set at 0.05. The average bone healing scores per group were as follows: C group, 12.5; A group, 26.5; ACS group, 18.8; B-TCP group, 26.2; HA group, 20.9; and B group, 20.9. The C group showed a significant difference between weeks 4 and 8 (p = 0.032). Among the 4-week groups, the C group showed a significant difference compared to A (p = 0.001), ACS (p = 0.017), and B-TCP (p = 0.005) groups. The 8-week experimental group did not show any significant differences between the groups. The 5-mm critical size defect in rat calvaria requires the use of bone biomaterials to heal at 4 and 8 weeks. rhBMP-2, as applied in this study, showed no difference in new bone formation when combined with bovine, B-TCP, or HA biomaterials.

3D printed calcium phosphate scaffolds with controlled release of osteogenic drugs for bone regeneration

The purpose of this research was to repair critical size defects of a skull. First, the CT data on the Beagle's skull were used to reconstruct an implant model. Then two Ф15 mm critical bone defects on the left and right sides of the skull were drilled. Hydroxyapatite, sodium alginate and icariin were adopted to formulate the printing inks according to their proportions. Calcium phosphate scaffolds with accuracy porosity were 3D printed by an extrusion printer. Icariin served as a controlled release of osteogenic drugs for bone regeneration. The physical and chemical properties of the 3D printed scaffolds were summarized, and in vitro and in vivo tests were conducted to assess the biocompatibility and the bone repair ability of the scaffolds. According to the mechanical results, the 3D printed calcium phosphate scaffolds show improved mechanical strength, and the Young's modulus was about 4.23 MPa, while the compressive strength was 9.37 MPa. The drug release test results showed that the slowly controlled release of osteogenic drugs behavior by the 3D printed calcium phosphate scaffolds continuously promoted new bone formation. The in vitro biological assessment results suggested that the 3D printed calcium phosphate scaffolds had good biocompatibility, with no obvious cytotoxicity observed. An animal model, aimed at achieving personalized accurate repair of the critical size defects on the skull, indicated that the 3D printed calcium phosphate scaffolds with controlled release of osteogenic drugs had great potential for regeneration of critical bone defects.

Comparison of amniotic membrane versus the induced membrane for bone regeneration in long bone segmental defects using calcium phosphate cement loaded with BMP-2

Thanks to its biological properties, the human amniotic membrane (HAM) combined with a bone substitute could be a single-step surgical alternative to the two-step Masquelet induced membrane (IM) technique for regeneration of critical bone defects. However, no study has directly compared these two membranes.We first designed a 3D-printed scaffold using calcium phosphate cement (CPC). We assessed its suitability in vitro to support human bone marrow mesenchymal stromal cells (hBMSCs) attachment and osteodifferentiation. We then performed a rat femoral critical size defect to compare the two-step IM technique with a single-step approach using the HAM. Five conditions were compared. Group 1 was left empty. Group 2 received the CPC scaffold loaded with rh-BMP2 (CPC/BMP2). Group 3 and 4 received the CPC/BMP2 scaffold covered with lyophilized or decellularized/lyophilized HAM. Group 5 underwent a two- step induced membrane procedure with insertion of a polymethylmethacrylate (PMMA) spacer followed by, after 4 weeks, its replacement with the CPC/BMP2 scaffold wrapped in the IM. Micro-CT and histomorphometric analysis were performed after six weeks.Results showed that the CPC scaffold supported the proliferation and osteodifferentiation of hBMSCs in vitro. In vivo, the CPC/BMP2 scaffold very efficiently induced bone formation and led to satisfactory healing of the femoral defect, in a single-step, without autograft or the need for any membrane covering. In this study, there was no difference between the two-step induced membrane procedure and a single step approach. However, the results indicated that none of the tested membranes further enhanced bone healing compared to the CPC/BMP2 group.

Comparative Analysis of the Effect of Two Therapeutic Ultrasound Protocols for Regeneration of a Critical Bone Defect.

Objective To compare the effect of two therapeutic ultrasound protocols, with different times of exposure in the regeneration of critical bone defect. Methods Forty-five male rats were distributed among three experimental groups: therapeutic ultrasound group 5 minutes (TUG 5); therapeutic ultrasound group 10 minutes (TUG 10); and control group (CG). In all groups, a critical bone defect of 8.5 mm diameter was made in the calvaria region. The protocol was initiated on the 1 st postoperative day in TUGs 5 and 10, with therapeutic ultrasound at the frequency of 1.0 MHz, pulsed mode, five times a week, at periods of 15, 30, and 60 days. Results Among the experimental groups, the highest volume of neoformation of osteoid matrix took place in the TUG 10 group followed by TUG 5, when compared with the CG group, in which the neoformation was restricted to the border region. The use of ultrasound promoted an increase in the thickness of the conjunctive matrix, proliferation of capillaries, alignment of the collagen fibers, reduction of edema and inflammatory process, being more significant in the 10-minutes time period. Conclusion Therapeutic ultrasound stimulated the repair of a critical bone defect, and the longer exposure time promoted greater osteogenic stimulation.

The regeneration of critical bone defects with mononuclear fraction in rat calvaria

The regeneration of critical bone defects with mononuclear fraction in rat calvaria

Histomorphometric evaluation of bone regeneration using autogenous bone and beta-tricalcium phosphate in diabetic rabbits.

The mechanism of impaired bone healing in diabetes mellitus includes different tissue and cellular level activities due to micro- and macrovascular changes. As a chronic metabolic disease with vascular complications, diabetes affects a process of bone regeneration as well. The therapeutic approach in bone regeneration is based on the use of osteoinductive autogenous grafts as well as osteoconductive synthetic material, like a β-tricalcium phosphate. The aim of the study was to determine the quality and quantity of new bone formation after the use of autogenous bone and β-tricalcium phosphate in the model of calvarial critical-sized defect in rabbits with induced diabetes mellitus type I. The study included eight 4-month-old Chincilla rabbits with alloxan-induced diabetes mellitus type I. In all animals, there were surgically created two calvarial bilateral defects (diameter 12 mm), which were grafted with autogenous bone and β-tricalcium phosphate (n = 4) or served as unfilled controls (n = 4). After 4 weeks of healing, animals were sacrificed and calvarial bone blocks were taken for histologic and histomorphometric analysis. Beside descriptive histologic evaluation, the percentage of new bone formation, connective tissue and residual graft were calculated. All parameters were statistically evaluated by Friedman Test and post hock Wilcoxon Singed Ranks Test with a significance of p < 0.05. Histology revealed active new bone formation peripherally with centrally located connective tissue, newly formed woven bone and well incorporated residual grafts in all treated defects. Control samples showed no bone bridging of defects. There was a significantly more new bone in autogeonous graft (53%) compared with β-tricalcium phosphate (30%), (p < 0.030) and control (7%), (p < 0.000) groups. A significant difference was also recorded between β-tricalcium phosphate and control groups (p < 0.008). In the present study on the rabbit grafting model with induced diabetes mellitus type I, the effective bone regeneration of critical bone defects was obtained using autogenous bone graft. [Projekat Ministarstva nauke Republike Srbije, br. 175021].

Regeneration of critical bone defects with anionic collagen matrix as scaffolds

The aim of this study was to make a histomorphometric evaluation of the osteogenic potential of anionic collagen matrix as scaffolds; either crosslinked in glutaraldehyde or not cross-linked and, implanted in critical bone defects in rat calvaria. Seventy-two rats were randomly distributed in three groups: anionic collagen scaffolds treated for 24 h of selective hydrolysis (ACSH); anionic collagen scaffolds treated for 24 h of selective hydrolysis and 5 min of crosslinking in glutaraldehyde 0.05% (ACSHGA); empty bone defect (Control), evaluated at the biological points of 15, 45, 90 and 120 days. The results showed that the biomaterials implanted were biocompatible and showed a high osteogenic potential. These biomaterials presented a speed of biodegradation compatible with bone neoformation, which was shown to be associated with angiogenesis inside the scaffolds at all biological points. The percentage of mineralization of ACSH (87%) differed statistically from that found in ACSHGA (66%). It was concluded that the regeneration of critical bone defect was more evident in anionic collagen without crosslinking (ACSH).

Enhanced Regeneration of Critical Bone Defects Using a Biodegradable Gelatin Sponge and β-Tricalcium Phosphate with Bone Morphogenetic Protein-2

We examine the osteogenicity of a sponge biomaterial consisting of a biodegradable mixture of gelatin and beta-tricalcium phosphate (betaTCP) that bound bone morphogenetic protein 2 (BMP-2) in critical-sized bone defects in rats. Gelatin-betaTCP sponges containing either phosphate buffered saline or incorporating BMP-2 are implanted into 5 mm diameter bone defects created in rat mandibles. We assess the defects biweekly for 8 weeks following implantation. There is significantly higher osteoinductive activity and significantly more Gla-osteocalcin content at bone-defect healing sites treated with gelatin-betaTCP sponges incorporating BMP-2 than there is in those treated with sponges that did not contain BMP-2. Histologically, new bone that contains bone marrow and that is connected to the original bone almost entirely replaces the regenerated bone. These results show that biodegradable gelatin-betaTCP incorporating BMP-2 is osteogenic enough to promote healing in large bone defects.