Perigraft vascularization and incorporation of implanted Dacron prostheses are affected by rifampicin coating

Intrinsic antibacterial and osteoinductive sterosomes promote infected bone healing

Open fractures and internal fixation implants are often accompanied by bacterial infection, leading to osteomyelitis, characterized by intractable bone infection and sequestrum formation, and can result in lifelong disability or fatal sepsis. As common clinical treatment strategies, high-dose antibiotic application and autologous bone transplantation face the risk of recurrence and donor site injury. Herein, we designed and prepared a novel drug delivery system by rational selection of the antibacterial single-chain amphiphile (cetylpyridinium chloride, CPC) and osteoinductive sterol (20S-hydroxycholesterol, Oxy) to formulate CPC/Oxy sterosomes. We demonstrate their excellent biocompatibility and antibacterial ability through 2D and 3D settings in vitro. In addition, the osteogenic differentiation of bone marrow mesenchymal stem cells was investigated in cell monolayers and a hydrogel environment. Moreover, a rat infected critical-sized calvarial defect model was employed to illustrate the effects of antibacterial and osteogenic CPC/Oxy sterosomes in vivo. Our results showed that CPC/Oxy sterosomes not only exterminated bacterial infections, but also enhanced calvarial healing without additional antibiotics, bone formation promoters or exogenous cells. This research provides a promising and effective multifunctional sterosomal platform for the treatment of infected bone defects, with the potential to be combined with therapeutic genes, and small molecule drugs.

Screening of Biomarkers and Toxicity Mechanisms of Rifampicin-Induced Liver Injury Based on Targeted Bile Acid Metabolomics

Rifampicin (RIF) is a critical first-line drug for tuberculosis. However, long-term or high-dose treatment with RIF can induce severe liver injury; the underlying mechanism of this effect has not yet been clarified. This study was performed to screen reliable and sensitive biomarkers in serum bile acids (BAs) using targeted BA metabolomics and evaluate the toxicity mechanisms underlying RIF-induced liver injury through the farnesoid x receptor (Fxr)-multidrug resistance-associated proteins (Mrps) signaling pathway. Thirty-two Institute of Cancer Research mice were randomly divided into four groups, and normal saline, isoniazid 75 mg/kg + RIF 177 mg/kg (RIF-L), RIF-L, or RIF 442.5 mg/kg (RIF-H) was orally administered by gavage for 21 days. After treatment, changes in serum biochemical parameters, hepatic pathological conditions, BA levels, Fxr expression, and BA transporter levels were measured. RIF caused notable liver injury and increased serum cholic acid (CA) levels. Decline in the serum secondary BAs (deoxycholic acid, lithocholic acid, taurodeoxycholic acid, and tauroursodeoxycholic acid) levels led to liver injury in mice. Serum BAs were subjected to metabolomic assessment using partial least squares discriminant and receiver operating characteristic curve analyses. CA, DCA, LCA, TDCA, and TUDCA are potential biomarkers for early detection of RIF-induced liver injury. Furthermore, RIF-H reduced hepatic BA levels and elevated serum BA levels by suppressing the expression of Fxr and Mrp2 messenger ribonucleic acid (mRNA) while inducing that of Mrp3 and Mrp4 mRNAs. These findings provide evidence for screening additional biomarkers based on targeted BA metabolomics and provide further insights into the pathogenesis of RIF-induced liver injury.

Foreign body response to synthetic polymer biomaterials and the role of adaptive immunity

Implanted biomaterials elicit a series of distinct immune and repair-like responses that are collectively known as the foreign body reaction (FBR). These include processes involving innate immune inflammatory cells and wound repair cells that contribute to the encapsulation of biomaterials with a dense collagenous and largely avascular capsule. Numerous studies have shown that the early phase is dominated by macrophages that fuse to form foreign body giant cells that are considered a hallmark of the FBR. With the advent of more precise cell characterization techniques, specific macrophage subsets have been identified and linked to more or less favorable outcomes. Moreover, studies comparing synthetic- and natural-based polymer biomaterials have allowed the identification of macrophage subtypes that distinguish between fibrotic and regenerative responses. More recently, cells associated with adaptive immunity have been shown to participate in the FBR to synthetic polymers. This suggests the existence of cross-talk between innate and adaptive immune cells that depends on the nature of the implants. However, the exact participation of adaptive immune cells, such as T and B cells, remains unclear. In fact, contradictory studies suggest either the independence or dependence of the FBR on these cells. Here, we review the evidence for the involvement of adaptive immunity in the FBR to synthetic polymers with a focus on cellular and molecular components. In addition, we examine the possibility that such biomaterials induce specific antibody responses resulting in the engagement of adaptive immune cells.

Perigraft reaction and incorporation of porcine and bovine pericardial patches

OBJECTIVES

Bovine and porcine pericardial patches are frequently used in cardiothoracic and vascular surgery. There are no guidelines recommending the usage of these patches for particular surgical approaches. However, these 2 materials supposedly possess different properties. The clinical advantage of porcine compared with bovine patches remains controversial. In this experimental study, we analysed the incorporation and vascularization of bovine and porcine pericardial patches during the initial phase after implantation.

METHODS

Bovine and porcine pericardial patches were implanted into the dorsal skinfold chamber of C57BL/6 mice (n = 8 per group) to study vascularization and inflammation at the implantation site using repetitive intravital fluorescence microscopy over a 14-day period. At the end of the in vivo experiments, CD-31-positive cells were determined to evaluate the vascularization by immunohistochemistry. Furthermore, cell proliferation and apoptosis were analysed immunohistochemically.

RESULTS

Implanted bovine patches exhibited an enhanced vascularization, as indicated by a significantly higher number of CD-31-positive cells and micro-vessels (23.2 ± 4.3 vs 16.5 ± 5.8 mm-2; P = 0.001). Furthermore, bovine patches showed a slightly but not significantly higher functional capillary density. Both patches induced a moderate leukocytic inflammatory host tissue response, and neither bovine nor porcine patches significantly affected apoptosis and cell proliferation at the implantation site.

CONCLUSIONS

Bovine and porcine pericardial patches are similarly suitable for surgery. Bovine patches exhibited an improved vascularization during the first 14 days after implantation. This may result in a quicker and improved incorporation into the surrounding tissue compared with porcine pericardial patches.

Fusion peptide engineered "statically-versatile" titanium implant simultaneously enhancing anti-infection, vascularization and osseointegration

Although antimicrobial titanium implants can prevent biomaterial-associated infection (BAI) in orthopedics, they display cytotoxicity and delayed osseointegration. Therefore, versatile implants are desirable for simultaneously inhibiting BAI and promoting osseointegration, especially "statically-versatile" ones with nonessential external stimulations for facilitating applications. Herein, we develop a "statically-versatile" titanium implant by immobilizing an innovative fusion peptide (FP) containing HHC36 antimicrobial sequence and QK angiogenic sequence via sodium borohydride reduction promoted Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC-SB), which shows higher immobilization efficiency than traditional CuAAC with sodium ascorbate reduction (CuAAC-SA). The FP-engineered implant exhibits over 96.8% antimicrobial activity against four types of clinical bacteria (S. aureus, E. coli, P. aeruginosa and methicillin-resistant S. aureus), being stronger than that modified with mixed peptides. This can be mechanistically attributed to the larger bacterial accessible surface area of HHC36 sequence. Notably, the implant can simultaneously enhance cellular proliferation, up-regulate expressions of angiogenesis-related genes/proteins (VEGF and VEGFR-2) of HUVECs and osteogenesis-related genes/proteins (ALP, COL-1, RUNX-2, OPN and OCN) of hBMSCs. In vivo assay with infection and non-infection bone-defect model reveals that the FP-engineered implant can kill 99.63% of S. aureus, and simultaneously promote vascularization and osseointegration. It is believed that this study presents an excellent strategy for developing "statically-versatile" orthopedic implants.

In Vivo Biocompatibility of a Novel Expanded Polytetrafluoroethylene Suture for Annuloplasty

BACKGROUND

Expanded polytetrafluoroethylene (ePTFE) is a suture material for annuloplasty in aortic valve repair. For this particular application, it should induce minimal local stress and promote rapid tissue incorporation. To achieve this, a novel ePTFE suture with a larger diameter and high porosity in its midsection has been developed. Herein, we analyzed the acute and chronic tissue reaction to this suture material compared with a commercially available control ePTFE suture.

METHODS

Novel and control suture samples were implanted into dorsal skinfold chambers of BALB/c mice to analyze the early inflammatory response using intravital fluorescence microscopy over 14 days. Additional suture samples were implanted for 4 and 12 weeks in the flank musculature of mice and analyzed by histology and immunohistochemistry.

RESULTS

The implantation of novel and control ePTFE suture into the dorsal skinfold chamber did not induce an acute inflammation, as indicated by physiological numbers of rolling and adherent leukocytes in all analyzed venules. Chronic implantation into the flank musculature showed a better tissue incorporation of the novel ePTFE suture with more infiltrating cells and a higher content of Sirius red+ collagen fibers when compared with controls. Cell proliferation and viability as well as numbers of recruited CD68+ macrophages, myeloperoxidase+ neutrophilic granulocytes and CD3+ lymphocytes did not significantly differ between the groups.

CONCLUSION

The novel ePTFE suture exhibits a good in vivo biocompatibility which is comparable to that of the control suture. Due to its improved tissue incorporation, it may provide a better long-term stability during annuloplasty.