Perspectives on the prevention and treatment of infection for orthopedic tissue engineering applications

Advances in ionic liquid-based antimicrobial wound healing platforms

Wound infections, marked by the proliferation of microorganisms at surgical sites, necessitate the development of innovative wound dressings with potent bactericidal properties to curb microbial growth and prevent bacterial infiltration. This study explores the recent strides in utilizing ionic liquid-based polymers as highly promising antimicrobial agents for advanced wound healing applications. Specifically, cationic polymers containing quaternary ammonium, imidazolium, guanidinium, pyridinium, triazolium, or phosphonium groups have emerged as exceptionally effective antimicrobial compounds. Their mechanism of action involves disrupting bacterial membranes, thereby preventing the development of resistance and minimizing toxicity to mammalian cells. This comprehensive review not only elucidates the intricate dynamics of the skin's immune response and the various stages of wound healing but also delves into the synthesis methodologies of ionic liquid-based polymers. By spotlighting the practical applications of antimicrobial wound dressings, particularly those incorporating ionic liquid-based materials, this review aims to lay the groundwork for future research endeavors in this burgeoning field. Through a nuanced examination of these advancements, this article seeks to contribute to the ongoing progress in developing cutting-edge wound healing platforms that can effectively address the challenges posed by microbial infections in surgical wounds.

Effects of intra-articular D-amino acids combined with systemic vancomycin on an experimental Staphylococcus aureus-induced periprosthetic joint infection

BACKGROUND

The D-isoforms of amino acids (D-AAs) exhibit anti-biofilm potential against a diverse range of bacterial species in vitro, while its role in vivo remains unclear. The aim of this study was to investigate the effects of a combination of D-AAs and vancomycin on a PJI rat model.

METHODS

Eight-week-old male SD rats were randomized to the control group, sham group, vancomycin group, D-AAs-vancomycin group. After treatment for 6 weeks, we analysed the levels of inflammatory factors in serum, behavioural change, imaging manifestations. The anti-biofilm ability of D-AAs was detected by crystal violet staining and scanning electron microscope observation, and its ability to assist antibiotics in killing bacteria was assessed by culture of bacteria. Additionally, micro-CT and histological analysis were used to evaluate the impact of D-AAs combined with vancomycin on the bone remodelling around the prosthesis.

RESULTS

The group treated with a D-AAs-vancomycin combination sustained normal weight gain and exhibited reduced the serum levels of α2M, IL-1β, IL-6, IL-10, TNF-α and PGE2. Moreover, treated with D-AAs in combination with vancomycin improved the weight-bearing activity performance, increased the sizes and widths of distal femurs, and improved Rissing scale scoring. In particular, treatment using D-AAs enhanced the ability of vancomycin to eradicate Staphylococcus aureus, as demonstrated by the dispersion of existing biofilms and the inhibition of biofilm formation that occurred in a concentration-dependent manner. This treatment combination also resulted in a reduction in bacterial burden with in the soft tissues, bones, and implants. Furthermore, D-AAs-vancomycin combination treatment attenuated abnormal bone remodelling around the implant, as evidenced by an observed increase in BMD, BV/TV, and Tb.Th and the presence of reduced Trap⁺ osteoclasts and elevated osterix⁺ osteo-progenitors.

CONCLUSIONS

Combining D-AAs with vancomycin provides an effective therapeutic strategy for the treatment of PJI by promoting biofilm dispersion to enhance antimicrobial activity.

Recent Advances on Bacterial Cellulose-Based Wound Management: Promises and Challenges

Wound healing is a therapeutic challenge due to the complexity of the wound. Various wounds could cause severe physiological trauma and bring social and economic burdens to the patient. The conventional wound healing treatments using bandages and gauze are limited particularly due to their susceptibility to infection. Different types of wound dressing have developed in different physical forms such as sponges, hydrocolloids, films, membranes, and hydrogels. Each of these formulations possesses distinct characteristics making them appropriate for the treatment of a specific wound. In this review, the pathology and microbiology of wounds are introduced. Then, the most recent progress on bacterial cellulose- (BC-) based wound dressing discussed and highlighted their antibacterial and reepithelization properties in vitro and in vivo wound closure. Finally, the challenges and future perspectives on the development of BC-based wound dressing biomaterials are outlined.

Advances in Waterborne Polyurethane-Based Biomaterials for Biomedical Applications

Polyurethane (PU) is one of the most popular synthetic elastomers and widely employed in biomedical fields owing to the excellent biocompatibility and hemocompatibility known today. In addition, PU is simply prepared and its mechanical properties such as durability, elasticity, elastomer-like character, fatigue resistance, compliance or tolerance in the body during the healing, can be mediated by modifying the chemical structure. Furthermore, modification of bulk and surface by incorporating biomolecules such as anticoagulant s or biorecognizable groups, or hydrophilic/hydrophobic balance is possible through altering chemical groups for PU structure. Such modifications have been designed to improve the acceptance of implant. For these reason, conventional solventborne (solvent-based) PUs have established the standard for high performance systems, and extensively used in medical devices such as dressings, tubing, antibacterial membrane , catheters to total artificial heart and blood contacting materials, etc. However, waterborne polyurethane (WPU) has been developed to improve the process of dissolving PU materials using toxic organic solvents, in which water is used as a dispersing solvent. The prepared WPU materials have many advantages, briefly (1) zero or very low levels of organic solvents, namely environmental-friendly (2) non-toxic, due to absence of isocyanate residues, and (3) good applicability caused by extensive structure/property diversity as well as an environment-friendly fabrication method resulting in increasing applicability. Therefore, WPUs are being in the spotlight as biomaterials used for biomedical applications . The purpose of this review is to introduce an environmental- friendly synthesis of WPU and consider the manufacturing process and application of WPU and/or WPU based nanocomposites as the viewpoint of biomaterials.

Tissue Engineering in Orthopaedics

➤It is important to carefully select the most appropriate combination of scaffold, signals, and cell types when designing tissue engineering approaches for an orthopaedic pathology.➤Although clinical studies in which the tissue engineering paradigm has been applied in the treatment of orthopaedic diseases are limited in number, examining them can yield important lessons.➤While there is a rapid rate of new discoveries in the basic sciences, substantial regulatory, economic, and clinical issues must be overcome with more consistency to translate a greater number of technologies from the laboratory to the operating room.

Levofloxacin-loaded star poly(ε-caprolactone) scaffolds by additive manufacturing

The employment of a tissue engineering scaffold able to release an antimicrobial agent with a controlled kinetics represents an effective tool for the treatment of infected tissue defects as well as for the prevention of scaffolds implantation-related infectious complications. This research activity was aimed at the development of additively manufactured star poly(ε-caprolactone) (*PCL) scaffolds loaded with levofloxacin, investigated as antimicrobial fluoroquinolone model. For this purpose a computer-aided wet-spinning technique allowing functionalizing the scaffold during the fabrication process was explored. Scaffolds with customized composition, microstructure and anatomical external shape were developed by optimizing the processing parameters. Morphological, thermal and mechanical characterization showed that drug loading did not compromise the fabrication process and the final performance of the scaffolds. The developed *PCL scaffolds showed a sustained in vitro release of the loaded antibiotic for 5 weeks. The proposed computer-aided wet-spinning technique appears well suited for the fabrication of anatomical scaffolds endowed with levofloxacin-releasing properties to be tested in vivo for the regeneration of long bone critical size defects in a rabbit model.