Safety of Irradiated Homologous Costal Cartilage Graft in Cleft Rhinoplasty.

BACKGROUND: Autologous cartilage grafts have a low risk of infection and extrusion in cleft rhinoplasty. However, harvesting autologous cartilage involves donor-site morbidity and increased time under anesthesia. Irradiated homologous costal cartilage grafts may be an effective alternative. METHODS: A retrospective study was performed on patients with a history of cleft lip who underwent rhinoplasty for cleft nasal deformity at Johns Hopkins Hospital from 2009 to 2018. Patients were excluded if their rhinoplasty did not involve a cartilage graft. RESULTS: One hundred sixty-five cleft rhinoplasties (patient age, 2 to 72 years; 52 percent female) were performed. Median follow-up time was 256 days; 30 percent were revision operations. Ninety-six procedures (58 percent) used irradiated homologous costal cartilage grafts, with the remaining using autologous cartilage. Complications resulted from 18 procedures (11 percent), seven (10 percent) involving autologous cartilage and 11 (12 percent) involving irradiated homologous costal cartilage. Most autologous cartilage complications (86 percent) required operative intervention, versus seven of 11 (64 percent) for irradiated homologous costal cartilage. Complications associated with irradiated homologous costal cartilage included infection (n = 5), warping (n = 2), and extrusion (n = 1), while two patients with autologous cartilage experienced collapse and one each experienced resorption, warping, and hypertrophic donor-site scarring. There was no difference between groups regarding complication rate or complications requiring operative intervention (p = 0.3 and p = 0.5, respectively). CONCLUSIONS: Irradiated homologous costal cartilage grafts are equally safe and effective as autologous cartilage for use in cleft rhinoplasty. These grafts are readily available and eliminate donor-site morbidity. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.

Spatial heterogeneity of bacterial colonization across different gut segments following inter-species microbiota transplantation.

BACKGROUND: The microbiota presents a compartmentalized distribution across different gut segments. Hence, the exogenous microbiota from a particular gut segment might only invade its homologous gut location during microbiota transplantation. Feces as the excreted residue contain most of the large-intestinal microbes but lack small-intestinal microbes. We speculated that whole-intestinal microbiota transplantation (WIMT), comprising jejunal, ileal, cecal, and colonic microbiota, would be more effective for reshaping the entire intestinal microbiota than conventional fecal microbiota transplantation fecal microbiota transplantation (FMT). RESULTS: We modeled the compartmentalized colonization of the gut microbiota via transplanting the microbiota from jejunum, ileum, cecum, and colon, respectively, into the germ-free mice. Transplanting jejunal or ileal microbiota induced more exogenous microbes' colonization in the small intestine (SI) of germ-free mice rather than the large intestine (LI), primarily containing Proteobacteria, Lactobacillaceae, and Cyanobacteria. Conversely, more saccharolytic anaerobes from exogenous cecal or colonic microbiota, such as Bacteroidetes, Prevotellaceae, Lachnospiraceae, and Ruminococcaceae, established in the LI of germ-free mice that received corresponding intestinal segmented microbiota transplantation. Consistent compartmentalized colonization patterns of microbial functions in the intestine of germ-free mice were also observed. Genes related to nucleotide metabolism, genetic information processing, and replication and repair were primarily enriched in small-intestinal communities, whereas genes associated with the metabolism of essential nutrients such as carbohydrates, amino acids, cofactors, and vitamins were mainly enriched in large-intestinal communities of germ-free mice. Subsequently, we compared the difference in reshaping the community structure of germ-free mice between FMT and WIMT. FMT mainly transferred LI-derived microorganisms and gene functions into the recipient intestine with sparse SI-derived microbes successfully transplanted. However, WIMT introduced more SI-derived microbes and associated microbial functions to the recipient intestine than FMT. Besides, WIMT also improved intestinal morphological development as well as reduced systematic inflammation responses of recipients compared with FMT. CONCLUSIONS: Segmented exogenous microbiota transplantation proved the spatial heterogeneity of bacterial colonization along the gastrointestinal tract, i.e., the microbiota from one specific location selectively colonizes its homologous gut region. Given the lack of exogenous small-intestinal microbes during FMT, WIMT may be a promising alternative for conventional FMT to reconstitute the microbiota across the entire intestinal tract. Video Abstract.

A porcine xenograft-derived bone scaffold is a biocompatible bone graft substitute: An assessment of cytocompatibility and the alpha-Gal epitope.

BACKGROUND: Xenografts are an attractive alternative to traditional bone grafts because of the large supply from donors with predictable morphology and biology as well as minimal risk of human disease transmission. Clinical series involving xenograft bone transplantation, most commonly from bovine sources, have reported poor results with frequent graft rejection and failure to integrate with host tissue. Failures have been attributed to residual alpha-Gal epitope in the xenograft which humans produce natural antibody against. To the authors' knowledge, there is currently no xenograft-derived bone graft substitute that has been adopted by orthopedic surgeons for routine clinical use. METHODS: In the current study, a bone scaffold intended to serve as a bone graft substitute was derived from porcine cancellous bone using a tissue decellularization and chemical oxidation protocol. In vitro cytocompatibility, pathogen clearance, and alpha-Gal quantification tests were used to assess the safety of the bone scaffold intended for human use. RESULTS: In vitro studies showed the scaffold was free of processing chemicals and biocompatible with mouse and human cell lines. When bacterial and viral pathogens were purposefully added to porcine donor tissue, processing successfully removed these pathogens to comply with sterility assurance levels established by allograft tissue providers. Critically, 98.5% of the alpha-Gal epitope was removed from donor tissue after decellularization as shown by ELISA inhibition assay and immunohistochemical staining. CONCLUSIONS: The current investigation supports the biologic safety of bone scaffolds derived from porcine donors using a decellularization protocol that meets current sterility assurance standards. The majority of the highly immunogenic xenograft carbohydrate was removed from donor tissue, and these findings support further in vivo investigation of xenograft-derived bone tissue for orthopedic clinical application.

Non-viral pathogens: Identification, relevance, and prevention for xenotransplantation.

BACKGROUND: For xenotransplantation, strategies to prevent transmission of microorganisms from the source animal to the human recipient must be closely coordinated since tissues and organs are classified as non-sterile. Strategies for international cooperation and coordination of xenogeneic infection / disease surveillance and response are available. METHODS: The regulatory frameworks and criteria on microbial safety as published by World Health Organization (WHO), European Pharmacopoeia (Ph. Eur.), European Medicines Agency (EMA) as well as U.S. Department of Health and Human Services (DHHS), Food and Drug Administration (FDA) and Center for Biologics Evaluation and Research (CBER), are outlined. RESULTS: Different sources of microbial germs are considered including potential infectious agents. Monitoring of livestock and testing of xenografts is accompanied by positive and negative controls to detect and to exclude tissue specific microorganisms such as bacteria. CONCLUSIONS: The criteria of microbial status to be considered for xenotransplants are summarized.

Procedure for Horizontal Transfer of Patient-Derived Xenograft Tumors to Eliminate Corynebacterium bovis.

Human patient-derived xenograft (PDX) tumors, propagated in immunodeficient mice, are rapidly growing in use as a model for cancer research. Horizontal transfer between mice, without in vitro cell culture, allows these tumors to retain many of their unique characteristics from their individual patient of origin. However, the immunodeficient mouse strains used to grow these tumors are susceptible to numerous opportunistic pathogens, including Corynebacterium bovis. At our institution, 2 in vivo tumor banks of PDX tumors had been maintained within nude mouse colonies enzootically infected with C. bovis. Elimination of C. bovis from these colonies required the aseptic harvest and horizontal transfer of tumor tissue between infected and naïve recipient mice without cross-contamination. Out of necessity, we developed a standard operating procedure using enhancements to traditional aseptic surgical technique with concurrent application of both procedural and physical barriers to prevent C. bovis transmission. By using these methods, all 61 unique PDX tumor models were successfully harvested from C. bovis-infected mice and transferred into recipient mice without transmission of infection. Our data demonstrate that, in situations where C. bovis-free colonies can be established and maintained, this procedure can successfully be used to eliminate C. bovis from an in vivo tumor bank of valuable PDX tumors.

Porcine xenografts vs. (cryopreserved) allografts in the management of partial thickness burns: is there a clinical difference?

Porcine xenografts and cryopreserved allografts are used for the management of partial thickness burns and both biological materials have strong advocates with regard to clinical performance, the possibility of disease transfer from donor to recipient and other clinical aspects. A literature analysis was performed in an attempt to investigate whether true (statistically significant) differences exist on clinical performance and on other determinants for use. Comparing the results of this study with a similar, previously published study performed on possible differences amongst different types of allograft in the management of partial thickness burns, both allografts and porcine xenograft seem to perform equally well clinically with regard to healing related outcomes. In addition, the risk of disease transfer, in real life, was shown to be minimal. Consequently, clinical aspects being equal, other aspects such as price and availability should be used to decide which material to use for the management of partial thickness burns.

Engrafted human cells generate adaptive immune responses to Mycobacterium bovis BCG infection in humanized mice.

BACKGROUND: Currently used mouse models fail to fully reflect human immunity to tuberculosis (TB), which hampers progress in research and vaccine development. Bone marrow-liver-thymus (BLT) mice, generated by engrafting human fetal liver, thymus, and hematopoietic stem cells in severely immunodeficient NOD/SCID/IL-2Rγ(-/-) (NSG) mice, have shown potential to model human immunity to infection. We engrafted HLA-A2-positive fetal tissues into NSG mice transgenically expressing human leukocyte antigen (HLA)-A2.1 (NSG-A2) to generate NSG-A2-BLT mice and characterized their human immune response to Mycobacterium bovis bacillus Calmette-Guerin (BCG) infection to assess the utility of this model for investigating human TB. RESULTS: NSG-A2-BLT mice were infected intravenously with BCG and the immune response of engrafted human immune cells was characterized. After ex vivo antigenic stimulation of splenocytes, interferon (IFN)-γ-producing cells were detected by ELISPOT from infected, but not uninfected NSG-A2-BLT mice. However, the levels of secreted IFN-γ, determined by ELISA, were not significantly elevated by antigenic stimulation. NSG-A2-BLT mice were susceptible to BCG infection as determined by higher lung bacillary load than the non-engrafted control NSG-A2 mice. BCG-infected NSG-A2-BLT mice developed lung lesions composed mostly of human macrophages and few human CD4+ or CD8+ T cells. The lesions did not resemble granulomas typical of human TB. CONCLUSIONS: Engrafted human immune cells in NSG-A2-BLT mice showed partial function of innate and adaptive immune systems culminating in antigen-specific T cell responses to mycobacterial infection. The lack of protection was associated with low IFN-γ levels and limited numbers of T cells recruited to the lesions. The NSG-A2-BLT mouse is capable of mounting a human immune response to M. tuberculosis in vivo but a quantitatively and possibly qualitatively enhanced effector response will be needed to improve the utility of this model for TB research.