Applications of Bacterial Cellulose-Based Composite Materials in Hard Tissue Regenerative Medicine

Bacterial cellulose: Is it really a promising biomedical material?

Bacterial cellulose (BC) is currently considered a promising biomaterial due to its specific structure and properties. However, despite extensive research, questions about its fundamental properties, especially biocompatibility, remain. Thus, the purpose of this review is to analyze the results of in vivo trials from different areas of biomedicine, including wound healing, tissue engineering, drug delivery, and biomedical implants. The primary question guiding our review was "Why is bacterial cellulose still not used in clinical practice?" Analysis of the literature has shown that the results of in vivo studies often contradict each other. For example, BC caused and did not cause an immune response in an equal number of reviewed articles. Its efficacy in pure form generally does not differ significantly from that of materials already on the market. Conversely, BC may prove to be a valuable material in the long term, not because of its efficacy, but rather because of its affordability and ease of use. Additionally, challenges associated with immune reactions, long-term biocompatibility, and the necessity for standardized experimental protocols must be addressed. We expect that this review will encourage a more thoughtful investigation of BC to bring it into practical medicine.

The potent osteo-inductive capacity of bioinspired brown seaweed-derived carbohydrate nanofibrous three-dimensional scaffolds

This study aimed to investigate the osteo-inductive capacity of a fucoidan polysaccharide network derived from brown algae on human adipose-derived stem cells (HA-MSCs) for bone regeneration. The physiochemical properties of the scaffold including surface morphology, surface chemistry, hydrophilicity, mechanical stiffness, and porosity were thoroughly characterized. Both in vitro and in vivo measurements implied a superior cell viability, proliferation, adhesion, and osteo-inductive performance of obtained scaffolds compared to using specific osteogenic induction medium with increased irregular growth of calcium crystallites, which mimic the structure of natural bones. That scaffold was highly biocompatible and suitable for cell cultures. Various examinations, such as quantification of mineralization, alkaline phosphatase, gene expression, and immunocytochemical staining of pre-osteocyte and bone markers confirmed that HAD-MSCs differentiate into osteoblasts, even without an osteogenic induction medium. This study provides evidence for the positive relationship and synergistic effects between the physical properties of the decellularized seaweed scaffold and the chemical composition of fucoidan in promoting the osteogenic differentiation of HA-MSCs. Altogether, the natural matrices derived from brown seaweed offers a sustainable, cost-effective, non-toxic bioinspired scaffold and holds promise for future clinical applications in orthopedics.

Biomineral-Based Composite Materials in Regenerative Medicine

Regenerative medicine aims to address substantial defects by amplifying the body's natural regenerative abilities and preserving the health of tissues and organs. To achieve these goals, materials that can provide the spatial and biological support for cell proliferation and differentiation, as well as the micro-environment essential for the intended tissue, are needed. Scaffolds such as polymers and metallic materials provide three-dimensional structures for cells to attach to and grow in defects. These materials have limitations in terms of mechanical properties or biocompatibility. In contrast, biominerals are formed by living organisms through biomineralization, which also includes minerals created by replicating this process. Incorporating biominerals into conventional materials allows for enhanced strength, durability, and biocompatibility. Specifically, biominerals can improve the bond between the implant and tissue by mimicking the micro-environment. This enhances cell differentiation and tissue regeneration. Furthermore, biomineral composites have wound healing and antimicrobial properties, which can aid in wound repair. Additionally, biominerals can be engineered as drug carriers, which can efficiently deliver drugs to their intended targets, minimizing side effects and increasing therapeutic efficacy. This article examines the role of biominerals and their composite materials in regenerative medicine applications and discusses their properties, synthesis methods, and potential uses.

Development and performance evaluation of a novel elastic bacterial nanocellulose/polyurethane small caliber artificial blood vessels

There is an increasing demand for small-diameter blood vessels. Currently, there is no clinically available small-diameter artificial vessel. Bacterial nanocellulose (BNC) has vast potential for applications in artificial blood vessels due to its good biocompatibility. At the same time, medical polyurethane (PU) is a highly elastic polymer material widely used in artificial blood vessels. This study reports a composite small-diameter BNC/PU conduit using a non-solvent-induced phase separation method with the highly hydrophilic BNC tube as the skeleton and the hydrophobic polycarbonate PU as the filling material. The results revealed that the compliance and mechanical matching of BNC/PU tubes were higher than BNC tubes; the axial/radial mechanical strength, burst pressure, and suture strength were significantly improved; the blood compatibility and cell compatibility were also excellent. The molecular and subcutaneous embedding tests showed that the composite tubes had lighter inflammatory reactions. The results of the animal substitution experiments showed that the BNC/PU tubes kept blood flow unobstructed without tissue proliferation after implantation in rats for 9 months. Thus, the BNC/PU small-diameter vascular prosthesis had the potential for long-term patency and acted as an ideal material for small-diameter vessels.