Biology subjects

Rabbani, P. S.

Publications and source records attributed to Rabbani, P. S..

5 recordsLinked to original sources

bioRxiv2025

Preservation Strategies for Vascularized Composite Allotransplantation: An Updated Systematic Review of a Rapidly Expanding Field

BackgroundVascularized composite allotransplantation has become a viable reconstructive option for selected patients, but preservation remains a major barrier to broader clinical application. Static cold storage is the current gold standard, yet ischemia reperfusion injury and limited preservation times restrict its effectiveness. Recent advances in machine perfusion and subzero non-freezing storage (or supercooling) have prompted renewed interest in optimizing graft viability. MethodsFollowing PRISMA guidelines, we systematically searched PubMed, EMBASE, and Cochrane, covering studies published from June 2022 through August 2025 for studies on ex vivo preservation of vascularized composite allotransplantations. Eligible articles included original studies in English evaluating postharvest, pretransplant preservation strategies. Data extracted were study design, preservation methods, perfusates, and primary outcomes. Risk of bias was assessed using SYRCLE for animal studies and JBI for human/cadaver studies. ResultsSeventeen studies met inclusion criteria: one on static cold storage, thirteen on machine perfusion, and three on supercooling. Static cold storage research has declined, with the only recent study investigating sub-normothermic machine perfusion as a recovery adjunct. Machine perfusion studies focused on optimization of perfusion parameters, perfusate composition, and circuit design. Red blood cell-based perfusates remained common, but alternative oxygen carriers such as polymerized hemoglobin-based oxygen carrier-201 and dextran oxygen microcarriers showed promise despite edema-related challenges. Supercooling studies demonstrated feasibility of multi-day preservation in rodent and porcine models. Overall, risk of bias was high or unclear across animal studies, mainly due to selection and performance bias, whereas the single human ex vivo study showed low risk of bias. ConclusionsThe field of vascularized composite allograft preservation is expanding rapidly, with machine perfusion and supercooling emerging as the most promising strategies to extend graft viability beyond the limits of static cold storage. However, translation to clinical setting remains limited by small preclinical studies, methodological heterogeneity, and the paucity of functional and immunologic endpoints. Standardized protocols, robust large-animal models, and eventual human feasibility trials are needed to establish clinically applicable preservation strategies. Level of evidence: IV

bioengineering↗

bioRxiv2025

Non-segmented unsupervised learning of multispectral whole slide images for robust analysis of tissue repair and regeneration

Analyzing whole tissue architecture remains challenging due to the inherent complexity of multicellular organization, variable morphology, and the limitations of conventional segmentation-based image analysis. Traditional approaches often rely on partial sampling or nuclear/cytoplasmic boundaries, which risk introducing bias and fail to capture the contextual interplay of diverse tissue compartments. To overcome these barriers, we developed a segmentation free framework for analyzing multispectral whole slide images (WSIs). By tiling WSIs into fixed sized regions and extracting quantitative tile features, we applied unsupervised machine learning to systematically reveal patterns of tissue organization at scale. This approach preserved spatial context without the need for cell-level delineation, recapitulating expected compartments such as epidermis, adipose, and scab, while also revealing subtle but coherent substructures within stromal and granulation regions. Applied to murine wound healing, the method distinguished wild type from diabetic repair dynamics without prior labels, uncovering both gross and nuanced differences in tissue composition. Together, this work establishes a robust, unbiased strategy for whole-tissue analysis that circumvents the limitations of segmentation, leverages unsupervised learning for discovery, and advances the study of tissue repair and regenerative pathology.

cell biology↗

bioRxiv2024

Pre-treatments of Ex vivo Vascularized Composite Allografts: A Scoping Review

PURPOSEThe various physiological profiles comprising vascularized composite allografts (VCAs) pose unique challenges to preservation. Minimizing ischemia, reperfusion injury, and rejection remains a primary focus of graft pre-treatments (PTs). Currently, the gold standard PT consists of flushing the graft and placing it in static cold storage in the University of Wisconsin solution. With this method, graft viability is limited to four to six hours. Prolonging this time limit will increase donor allocation radius, access to care, and positive patient outcomes. We aimed to evaluate novel PTs that could potentially enhance and lengthen VCA viability. METHODSFollowing PRISMA guidelines, we conducted a comprehensive literature search of Embase, Cochrane, and PubMed. Studies had to be published prior to June 15, 2022. PTs had to target cell physiology, rather than immunogenicity. We extracted data including study design, PT details, evaluation metrics, and outcomes. RESULTSWe identified thirteen studies, categorized into three groups: solution-based alterations to the gold standard, ex vivo perfusion, and other novel techniques. The incorporation of hydrogen sulfide and Perfadex as solutions in the gold standard protocol demonstrated a six-day delay in rejection and limited reperfusion injury markers, respectively. In one ex vivo perfusion study, after 24 hours of PT and 12 hours post-transplant, VCA muscle contractility remained close to normal. The gold standard PT did not demonstrate the same success. However, graft weight gain, up to 50% of baseline among the articles reviewed, is a prominent side effect of perfusion. Another technique, cryopreservation, displayed 90% graft failure by venous thrombosis, despite high free graft viability following two weeks of storage. CONCLUSIONSThis study of pre-treatment modalities found a variety of encouraging preservation techniques for grafts with high levels of tissue diversity. Ex vivo perfusion dominated PT innovation with promising results in preserving the viability and functionality of muscle, which is central to the restoration of movement. Future studies are necessary to evaluate long-term graft outcomes and to optimize PT protocols for extended preservation times to ensure clinical relevance.

systems biology↗

bioRxiv2024

Functional high capacity exosome-encapsulating bioinspired hydrogel promotes microvascularbed expansion in diabetic mice

Chronic wounds present a significant clinical challenge due to impaired skin microvasculature, particularly in diabetes. The tissue engineering study introduces therapeutic Exo-Q, a unique thermoresponsive polymer hydrogel created with Q protein nanofibers and cultured human bone marrow multipotent stromal cell exosomes with consistent gene signature. Limited, local and topical application of Exo-Q hydrogel is feasible for maximum neovascularization during murine diabetic wound closure in a xenotransplantation model, as well as compatibility and vascular delivery in human skin in a xenograft model. Exo-Q hydrogel treatment significantly reduces diabetic wound closure time within ranges of non-diabetic wounds. This innovative, non-invasive tissue engineered therapeutic option offers a promising approach to addressing the complex pathologies of non-healing wounds.

bioengineering↗

bioRxiv2022

Evolution of a Plastic Surgery Summer Research Program

BackgroundEarly surgical exposure and research fellowships have been independently shown to influence medical students specialty choice, increase academic productivity, and impact residency match. However, to our knowledge there is no published guidance on the implementation of formal plastic surgery summer research programs for first year medical students. We present our institutional experience developing a plastic surgery summer research program over seven years (2013-2020) in an effort to inform program development at other institutions. We hypothesized that this early, formal exposure could spark interest in pursuing research activities throughout medical school and residency. MethodsFrom 2013 to 2016, a sole basic science research arm existed. In 2017, a clinical research arm was introduced, with several supplemental activities including structured surgical skills sessions. A formalized selection process was instituted in 2014. Participant feedback was analyzed on a yearly basis. Long-term outcomes included continued research commitment, productivity, and residency match. ResultsThe applicant pool has reached 96 applicants in 2019, with 85% from outside institutions. Acceptance rate reached 7% in 2020. With adherence to a scoring rubric for applicant evaluation, good to excellent interrater reliability was achieved (ICC = 0.75). Long-term outcomes showed that on average per year, 28% of participants continued departmental research activities and 29% returned for dedicated research. Upon finishing medical school, participants had a mean of 6.9{+/-}4.0 peer-reviewed publications. 62% of participants matched into a surgical residency program, with 54% in integrated plastic surgery. ConclusionsA research program designed for first year medical students interested in plastic surgery can achieve academic goals. Students are provided with mentorship, networking opportunities, and tools for self-guided learning and career development.

scientific communication and education↗