Hyper-Crosslinked Carbohydrate Polymer for Repair of Critical-Sized Bone Defects

In Vivo Performance of a Novel Hyper-Crosslinked Carbohydrate Polymer Bone Graft Substitute for Spinal Fusion

Bone graft materials are essential for achieving arthrodesis after spine surgery. Safe bone graft products, with osteoinductive, osteoconductive properties and the ability to monitor fusion in real-time, are highly desirable. A novel hyper-crosslinked carbohydrate polymer (HCCP) bone graft substitute was shown to aid in bone regeneration in critical-size defect studies in a rabbit model. These studies further evaluated the in vivo application of HCCP as a bone graft substitute in an ovine model of spinal fusion and a retrospective study in adult human spine surgery patients. Sheep studies demonstrated the safety and efficacy of HCCP with no evidence of adverse histopathology over 6 months of follow-up. In human studies, patients (N = 63) underwent posterolateral fusion with HCCP, with follow-up to assess fusion success. No adverse reaction related to the HCCP bone graft substitute was identified. Fusion success was noted to be non-inferior to other bone graft substitutes. HCCP appears to be a safe bone void filler adjunct for use in spinal fusion surgery for both trauma and degenerative disease. It has a good degradation profile for forming bone with the ability to provide new vasculature and may also function as a scaffold to carry cells, medications, and growth factors. Given the safety profile experienced in our preclinical and clinical studies, future investigation into its efficacy to achieve solid fusion is currently ongoing.

Use of a Novel Hypercrosslinked Carbohydrate Scaffold for Vocal Fold Medialization in an Ovine Model

Objectives

Vocal fold medialization is commonly performed for glottic insufficiency and vocal fold immobility. Currently available materials are temporary injectables or synthetic implants. Acellular scaffolds may allow vocal fold augmentation with autologous tissue via host cell migration. The purpose of this investigation was to evaluate the use of a novel carbohydrate scaffold as a medialization implant.

Study Design

Animal model.

Setting

Academic medical center.

Methods

Unilateral type I medialization thyroplasty was performed in 3 Dorper cross ewes using a hypercrosslinked carbohydrate polymer (HCCP) scaffold. Animals were monitored for 4 weeks for general well-being, dyspnea, and weight loss. The animals were euthanized at 4 weeks and the larynges harvested. Histologic evaluation was performed to assess for adverse tissue reaction, migration, degradation, and biocompatibility.

Results

No adverse events were reported. No animals lost weight or displayed evidence of dyspnea. Histology demonstrated ingrowth of host cells and neovascularization with minimal peri-implant inflammatory reaction. Cellular ingrowth into the scaffold was predominately made up of fibroblasts and early inflammatory cells. Scaffold shape was grossly maintained as it underwent degradation and replacement with host tissue. Migration of the implant material was not observed.

Conclusion

Vocal fold medialization in an ovine model with an HCCP scaffold resulted in the ingrowth of host cells with minimal peri-implant inflammation. Scaffold shape was maintained without evidence of migration as it underwent replacement with host tissue. Further research is required to assess long-term efficacy in comparison to currently available implants.

Preparation and Characterization of Hydrogel Films and Nanoparticles Based on Low-Esterified Pectin for Anticancer Applications

Prospective adjuvant anticancer therapy development includes the establishing of drug delivery systems based on biocompatible and biodegradable carriers. We have designed films and nanoparticles (NPs) based on low-esterified pectin hydrogel using the ionic gelation method. We investigated morphology, nanomechanical properties, biocompatibility and anticancer activity. Hydrogel films are characterized by tunable viscoelastic properties and surface nanoarchitectonics through pectin concentration and esterification degree (DE), expressed in variable pore frequency and diameter. An in vitro study showed a significant reduction in metabolic activity and the proliferation of the U87MG human glioblastoma cell line, probably affected via the adhesion mechanism. Glioma cells formed neurosphere-like conglomerates with a small number of neurites when cultured on fully de-esterified pectin films and they did not produce neurites on the films prepared on 50% esterified pectin. Pectin NPs were examined in terms of size distribution and nanomechanical properties. The NPs' shapes were proved spherical with a mean diameter varying in the range of 90-115 nm, and a negative zeta potential from -8.30 to -7.86 mV, which indicated their stability. The NPs did not demonstrate toxic effect on cells or metabolism inhibition, indicating good biocompatibility. Nanostructured biomaterials prepared on low-esterified pectins could be of interest for biomedical applications in adjuvant anticancer therapy and for designing drug delivery systems.

Biomedical applications of three-dimensional bioprinted craniofacial tissue engineering

Anatomical complications of the craniofacial regions often present considerable challenges to the surgical repair or replacement of the damaged tissues. Surgical repair has its own set of limitations, including scarcity of the donor tissues, immune rejection, use of immune suppressors followed by the surgery, and restriction in restoring the natural aesthetic appeal. Rapid advancement in the field of biomaterials, cell biology, and engineering has helped scientists to create cellularized skeletal muscle-like structures. However, the existing method still has limitations in building large, highly vascular tissue with clinical application. With the advance in the three-dimensional (3D) bioprinting technique, scientists and clinicians now can produce the functional implants of skeletal muscles and bones that are more patient-specific with the perfect match to the architecture of their craniofacial defects. Craniofacial tissue regeneration using 3D bioprinting can manage and eliminate the restrictions of the surgical transplant from the donor site. The concept of creating the new functional tissue, exactly mimicking the anatomical and physiological function of the damaged tissue, looks highly attractive. This is crucial to reduce the donor site morbidity and retain the esthetics. 3D bioprinting can integrate all three essential components of tissue engineering, that is, rehabilitation, reconstruction, and regeneration of the lost craniofacial tissues. Such integration essentially helps to develop the patient-specific treatment plans and damage site-driven creation of the functional implants for the craniofacial defects. This article is the bird's eye view on the latest development and application of 3D bioprinting in the regeneration of the skeletal muscle tissues and their application in restoring the functional abilities of the damaged craniofacial tissue. We also discussed current challenges in craniofacial bone vascularization and gave our view on the future direction, including establishing the interactions between tissue-engineered skeletal muscle and the peripheral nervous system.

Injectable Hyaluronic Acid/Human Umbilical Cord Mesenchymal Stem Cells/Bone Morphogenetic Protein-2 Promotes the Repair of Radial Bone Defects in Rabbits

Background: Bone defects are common in orthopedics and can be caused by congenital diseases, trauma, infection, tumors and other reasons. The treatment of large-scale bone defects is a clinical problem faced by orthopedists. The development of tissue engineering technology is expected to solve this problem. Objective: To explore the effect of injectable hyaluronic acid/hUCMSC/BMP-2 on the healing of rabbit radial bone defects. Methods: X-ray examination and tissue specimens were examined to macroscopically observe bone defect healing; tetracycline fluorescence and vonKossa staining were performed to observe the formation of new bone, and H&E staining was performed to examine cartilage and trabecular bone formation. Results: The injectable hyaluronic acid/hUCMSC/BMP-2 could significantly promote the early repair of bone defects and accelerate the process of bone formation. Conclusion: The direct injection of hyaluronic acid/hUCMSC/BMP-2 into afresh bone defect site has a significant beneficial effect on early repair of the bone defect.