Maxillofacial Reconstruction With Three Dimensional Resin Bone Substitutes as an Alternative to Transition Group of Metals: A Structured Review

In recent years, novel technologies and techniques have allowed today the production of controlled architecture materials. Although autogenous bone graft substitutes remain the gold standard, enormous defects require supplementary alloplastic substitutes for reconstruction. Polymers have lately been explored for the same purpose and their biological performance has been under research since the last decade. The aim of this review is to analyse maxillofacial reconstruction with three-dimensional resin bone substitutes. A Problem Intervention Comparison Outcomes (PICO) analysis was done and a search was carried out in the Cochrane Database, PubMed, Google Scholar etc databases and a hand search was done to collect the related literature. All articles for maxillofacial reconstruction with three-dimensional resin bone substitutes were scrutinised. The manuscripts published from 1990 till May 2021, were included in this review. A total of 106 articles were obtained from a PICO-based keyword search, and 91 manuscripts were retrieved after excluding the duplicates. Out of these 57 manuscripts were excluded on the basis of title and abstract. From the remaining 34 studies, 17 were excluded after reading the full text based on the inclusion and exclusion criteria. During data extraction, four studies were removed and finally, 13 studies were included in this research. From this scoping review, we could conclude that polymethylmethacrylate and polylactic acid formulations are very promising resin bone substitutes for 3-dimensional reconstruction of maxillofacial defects. However, rigorous long-term clinical trials are needed to validate this conclusion.

Photo-/thermo-responsive bioink for improved printability in extrusion-based bioprinting

Extrusion-based bioprinting has demonstrated significant potential for manufacturing constructs, particularly for 3D cell culture. However, there is a greatly limited number of bioink candidates exploited with extrusion-based bioprinting, as they meet the opposing requirements for printability with indispensable rheological features and for biochemical functionality with desirable microenvironment. In this study, a blend of silk fibroin (SF) and iota-carrageenan (CG) was chosen as a cell-friendly printable material. The SF/CG ink exhibited suitable viscosity and shear-thinning properties, coupled with the rapid sol-gel transition of CG. By employing photo-crosslinking of SF, the printability with Pr value close to 1 and structural integrity of the 3D constructs were significantly improved within a matter of seconds. The printed constructs demonstrated a Young's modulus of approximately 250 kPa, making them suitable for keratinocyte and myoblast cell culture. Furthermore, the high cell adhesiveness and viability (maximum >98%) of the loaded cells underscored the considerable potential of this 3D culture scaffold applied for skin and muscle tissues, which can be easily manipulated using an extrusion-based bioprinter.

Nanoporous and nano thickness film-forming bioactive composition for biomedical applications

Unmanageable bleeding is one of the significant causes of mortality. Attaining rapid hemostasis ensures subject survivability as a first aid during combats, road accidents, surgeries that reduce mortality. Nanoporous fibers reinforced composite scaffold (NFRCS) developed by a simple hemostatic film-forming composition (HFFC) (as a continuous phase) can trigger and intensify hemostasis. NFRCS developed was based on the dragonfly wing structure's structural design. Dragonfly wing structure consists of cross-veins and longitudinal wing veins inter-connected with wing membrane to maintain the microstructural integrity. The HFFC uniformly surface coats the fibers with nano thickness film and interconnects the randomly distributed cotton gauge (Ct) (dispersed phase), resulting in the formation of a nanoporous structure. Integrating continuous and dispersed phases reduce the product cost by ten times that of marketed products. The modified NFRCS (tampon or wrist band) can be used for various biomedical applications. The in vivo studies conclude that the developed Cp NFRCS triggers and intensifies the coagulation process at the application site. The NFRCS could regulate the microenvironment and act at the cellular level due to its nanoporous structure, which resulted in better wound healing in the excision wound model.

Biofabrication of allogenic bone grafts using cellularized amniotic scaffolds for application in efficient bone healing

INTRODUCTION

The reconstruction/regeneration of human bone injuries/defects represents a crucial challenge due to the lack of suitable bio/immune compatible and implantable biological grafts. The available strategies represent implications of several types of grafting materials in the form of metals, synthetic, and various kinds of biological scaffolds; however, the lack of appropriate biological components required for activating and enhancing repair mechanisms at the lesion-site limits their wider applicability.

METHODS

In this study, a unique approach for generating human osteogenic implantable grafts was developed using biofabrication technology. Using a gradient change of detergents and continuous agitation, developed a unique technique to generate completely cell-free amnion and chorion scaffolds. The absence of cellular components and integrity of biological and mechanical cues within decellularized human amnion (D-HAM) and chorion (D-HCM) were evaluated and compared with fresh membranes. Allogenic bone grafts were prepared through induction of human mesenchymal stem cells (hMSCs) into osteogenic cells on D-HAM and D-HCM and evaluated for their comparative behavior at the cellular, histological and molecular levels.

RESULTS

The common decellularization process resulted in an efficient way to generate D-HAM and D-HCM while retaining their intact gross-anatomical architecture, surface morphology, extracellular matrix components, and mechanical properties. Both these scaffolds supported better growth of human umbilical cord blood derived MSCs as well as osteogenic differentiation. Comparative investigation revealed better growth rate and differentiation on D-HCM compared to D-HAM and control conditions.

CONCLUSION

D-HCM could be used as a better choice for producing suitable allogenic bone grafts for efficient bone healing applications.

Decellularized Human Chorion Membrane as a Novel Biomaterial for Tissue Regeneration

Although some placenta-derived products are already used for tissue regeneration, the human chorion membrane (HCM) alone has been poorly explored. In fact, just one study uses decellularized HCM (dHCM) with native tissue architecture (i.e., without extracellular matrix (ECM) suspension creation) as a substrate for cell differentiation. The aim of this work is to fully characterize the dHCM for the presence and distribution of cell nuclei, DNA and ECM components. Moreover, mechanical properties, in vitro biological performance and in vivo biocompatibility were also studied. Our results demonstrated that the HCM was successfully decellularized and the main ECM proteins were preserved. The dHCM has two different surfaces, the reticular layer side and the trophoblast side; and is biocompatible both in vitro and in vivo. Importantly, the in vivo experiments demonstrated that on day 28 the dHCM starts to be integrated by the host tissue. Altogether, these results support the hypothesis that dHCM may be used as a biomaterial for different tissue regeneration strategies, particularly when a membrane is needed to separate tissues, organs or other biologic compartments.

A Sponge-Like Double-Layer Wound Dressing with Chitosan and Decellularized Bovine Amniotic Membrane for Promoting Diabetic Wound Healing

The diabetic wounds do not heal easily in part because they are susceptible to infection due to environmental influences. Wound dressing is crucial to wound healing, as it can basically protect the wound from external damages and provide a suitable microenvironment for tissue regeneration. In this study, a double-layer membrane that consists of chitosan sponge and decellularized bovine amniotic membrane (dBAM) has been developed by freeze-casting method. The results showed that the porous structure of the sponge layer improved the performances of blood coagulation and swelling. The dense dBAM can optimize the mechanical property of wound dressing. In vitro studies revealed that the bilayer membrane had favorable biocompatible, especially for human foreskin fibroblast cells (HFF-1) cell adhesion and proliferation. Moreover, the full-thickness skin defects of diabetic model mice that treated with bilayer membrane showed over 80% closure in 8 days. Our findings imply that the double-layer dressing has great potentials to be used in diabetic patients.