Three dimensional custom-made PEEK cranioplasty

Background: An optimal reconstruction of calvarial skull defects is a challenge for neurosurgeons, and the strategy used to achieve the best result remains debatable. Therefore, we conducted this study to compare the esthetic and functional outcome of custom-made three-dimensional (3D) cranioprostheses to handmade bone cement in reconstructing calvarial skull defects. Methods: We included 66 patients above 10 years of age with calvarial skull defects and undergoing reconstruction: 33 were enrolled in the custom-made 3D implants group and 33 in the handmade implants group in the period from August 2017 to December 2020 in the neurosurgery department of Fayoum University Hospital. Results: Complete success of the esthetic end-point was insignificantly higher in the custom-made 3D prostheses group based on the doctor’s and patients’ assessment (60.6% vs. 42.4%; 33.3% vs. 9.1%, P > 0.05), respectively. Complete success of the functional end-point was significantly higher in the custom-made 3D group compared to the handmade cement bone group according to the doctor’s and patients’ assessment (60.6% vs. 0%; 21.2% vs. 0%, P < 0.05). There were no late complications noted in the custom-made 3D prosthesis group, whereas 50% of the handmade bone group had late complications (P < 0.05). Full improvement of the symptoms of the “syndrome of trephined” was achieved in the 3D custom-made group compared to the handmade bone cement group (20% vs. 0%). Conclusion: Cranioplasty using three dimensional customs made PEEK prosthesis is a reliable method which saves operative time, lowers cost and provides less complications if compared with other cranioplasty techniques. Custom-made 3D cranioprostheses are better than handmade bone cement in reconstructing calvarial defects in terms of esthetic and functional outcome as well as complications.

Bone regeneration in rat calvarial defects using dissociated or spheroid mesenchymal stromal cells in scaffold-hydrogel constructs

Background Three-dimensional (3D) spheroid culture can promote the osteogenic differentiation of bone marrow mesenchymal stromal cells (BMSC). 3D printing offers the possibility to produce customized scaffolds for complex bone defects. The aim of this study was to compare the potential of human BMSC cultured as 2D monolayers or 3D spheroids encapsulated in constructs of 3D-printed poly-L-lactide-co-trimethylene carbonate scaffolds and modified human platelet lysate hydrogels (PLATMC-HPLG) for bone regeneration. Methods PLATMC-HPLG constructs with 2D or 3D BMSC were assessed for osteogenic differentiation based on gene expression and in vitro mineralization. Subsequently, PLATMC-HPLG constructs with 2D or 3D BMSC were implanted in rat calvarial defects for 12 weeks; cell-free constructs served as controls. Bone regeneration was assessed via in vivo computed tomography (CT), ex vivo micro-CT and histology. Results Osteogenic gene expression was significantly enhanced in 3D versus 2D BMSC prior to, but not after, encapsulation in PLATMC-HPLG constructs. A trend for greater in vitro mineralization was observed in constructs with 3D versus 2D BMSC (p > 0.05). In vivo CT revealed comparable bone formation after 4, 8 and 12 weeks in all groups. After 12 weeks, micro-CT revealed substantial regeneration in 2D BMSC (62.47 ± 19.46%), 3D BMSC (51.01 ± 24.43%) and cell-free PLATMC-HPLG constructs (43.20 ± 30.09%) (p > 0.05). A similar trend was observed in the histological analysis. Conclusion Despite a trend for superior in vitro mineralization, constructs with 3D and 2D BMSC performed similarly in vivo. Regardless of monolayer or spheroid cell culture, PLATMC-HPLG constructs represent promising scaffolds for bone tissue engineering applications.

Accelerated Bone Healing in Calvarial and Femoral Defects with Injectable Microcarriers that Mimic the Osteogenic Niche

Osteo-enhanced human mesenchymal stem cells (OEhMSCs) secrete an osteogenic cell matrix (OCM) that mimics the composition of anabolic bone tissue and strongly enhances OEhMSC retention and subsequent bone repair in vivo. Here we demonstrate a system for rapid production of gelatin methacrylate microcarriers coated with decellularized OCM (OCM-GelMA) to serve as an injectable bone graft material with high osteogenic potential comparable to a clinically utilized gold standard, bone morphogenic protein 2 (BMP-2). OEhMSCs seeded onto OCM-GelMA secreted high levels of osteogenic and angiogenic cytokines and expressed higher levels of BMP-2 relative to OEhMSCs on bare GelMA microcarriers. OEhMSCs co-administered with OCM-GelMA microcarriers resulted in enhanced healing of murine critical-sized calvarial defects, which was comparable to that achieved with a BMP-2-laden gelatin sponge control. When tested in a murine femoral defect model, OCM-GelMA co-administered with OEhMSCs also induced profound bone growth within the defect. We submit that OCM-GelMA promotes OEhMSC paracrine release to accelerate bone repair, indicating their potential as a bone graft for use in minimally invasive surgery.

Canine Mesenchymal Stromal Cell-Mediated Bone Regeneration is Enhanced in the Presence of Sub-Therapeutic Concentrations of BMP-2 in a Murine Calvarial Defect Model

Novel bone regeneration strategies often show promise in rodent models yet are unable to successfully translate to clinical therapy. Sheep, goats, and dogs are used as translational models in preparation for human clinical trials. While human MSCs (hMSCs) undergo osteogenesis in response to well-defined protocols, canine MSCs (cMSCs) are more incompletely characterized. Prior work suggests that cMSCs require additional agonists such as IGF-1, NELL-1, or BMP-2 to undergo robust osteogenic differentiation in vitro. When compared directly to hMSCs, cMSCs perform poorly in vivo. Thus, from both mechanistic and clinical perspectives, cMSC and hMSC-mediated bone regeneration may differ. The objectives of this study were twofold. The first was to determine if previous in vitro findings regarding cMSC osteogenesis were substantiated in vivo using an established murine calvarial defect model. The second was to assess in vitro ALP activity and endogenous BMP-2 gene expression in both canine and human MSCs. Calvarial defects (4 mm) were treated with cMSCs, sub-therapeutic BMP-2, or the combination of cMSCs and sub-therapeutic BMP-2. At 28 days, while there was increased healing in defects treated with cMSCs, defects treated with cMSCs and BMP-2 exhibited the greatest degree of bone healing as determined by quantitative μCT and histology. Using species-specific qPCR, cMSCs were not detected in relevant numbers 10 days after implantation, suggesting that bone healing was mediated by anabolic cMSC or ECM-driven cues and not via engraftment of cMSCs. In support of this finding, defects treated with cMSC + BMP-2 exhibited robust deposition of Collagens I, III, and VI using immunofluorescence. Importantly, cMSCs exhibited minimal ALP activity unless cultured in the presence of BMP-2 and did not express endogenous canine BMP-2 under any condition. In contrast, human MSCs exhibited robust ALP activity in all conditions and expressed human BMP-2 when cultured in control and osteoinduction media. This is the first in vivo study in support of previous in vitro findings regarding cMSC osteogenesis, namely that cMSCs require additional agonists to initiate robust osteogenesis. These findings are highly relevant to translational cell-based bone healing studies and represent an important finding for the field of canine MSC-mediated bone regeneration.

Cranioplasty

Calvarial defects are commonly encountered after neurosurgical procedures, trauma, and ablative procedures of advanced head neck cancers. The goals of cranioplasty are to provide a protective barrier for the intracranial contents, to restore form, and prevent syndrome of the trephined. Autologous and alloplastic techniques are available, each with their advantages and drawbacks. A multitude of materials are available for cranioplasty, and proper timing of reconstruction with attention to the overlying skin envelope is important in minimizing complications.

Bone Fracture-Treatment Method: Fixing 3D-Printed Polycaprolactone Scaffolds with Hydrogel Type Bone-Derived Extracellular Matrix and β-Tricalcium Phosphate as an Osteogenic Promoter

Bone formation and growth are crucial for treating bone fractures. Improving bone-reconstruction methods using autologous bone and synthetic implants can reduce the recovery time. Here, we investigated three treatments using two different materials, a bone-derived decellularized extracellular matrix (bdECM) and β-tricalcium phosphate (β-TCP), individually and in combination, as osteogenic promoter between bone and 3D-printed polycaprolactone scaffold (6-mm diameter) in rat calvarial defects (8-mm critical diameter). The materials were tested with a human pre-osteoblast cell line (MG63) to determine the effects of the osteogenic promoter on bone formation in vitro. A polycaprolactone (PCL) scaffold with a porous structure was placed at the center of the in vivo rat calvarial defects. The gap between the defective bone and PCL scaffold was filled with each material. Animals were sacrificed four weeks post-implantation, and skull samples were preserved for analysis. The preserved samples were scanned by micro-computed tomography and analyzed histologically to examine the clinical benefits of the materials. The bdECM–β-TCP mixture showed faster bone formation and a lower inflammatory response in the rats. Therefore, our results imply that a bdECM–β-TCP mixture is an ideal osteogenic promoter for treating fractures.