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The recellularization of tissues after decellularization is a relatively new technology in the field of tissue engineering (TE). Decellularization involves removing cells from a tissue or organ, leaving only the extracellular matrix (ECM). This can then be recellularized with new cells to create functional tissues or organs. The first significant mention of recellularization in decellularized tissues can be traced to research conducted in the early 2000s. One of the landmark studies in this field was published in 2008 by Ott, where researchers demonstrated the recellularization of a decellularized rat heart with cardiac cells, resulting in a functional organ capable of contraction. Since then, other important studies have been published. These studies paved the way for the widespread application of recellularization in TE, demonstrating the potential of decellularized ECM to serve as a scaffold for regenerating functional tissues. Thus, although the concept of recellularization was initially explored in previous decades, these studies from the 2000s marked a major turning point in the development and practical application of the technology for the recellularization of decellularized tissues. The article reviews the historical advances and limitations in organ recellularization in TE over the last two decades.
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Background: In practice, there is often a delay from initial debridement and temporary fixation to definitive soft tissue coverage of traumatic leg wounds. Without clear evidence, conservative negative pressure wound therapy (NPWT) is increasingly used to temporize these wounds. This systematic review summarizes and synthesizes the literature on using NPWT to temporize traumatic leg wounds before surgery in adult surgical patients. Methods: A comprehensive search of Medline, Embase, and Cochrane Library was performed from inception until July 2022, inclusively. Two independent reviewers performed screening, data extraction, and risk of bias assessment. Primary English studies, including adult patients (≥16 years old) with a fracture below the knee up to and including the ankle that received NPWT to temporize wounds before definitive soft tissue reconstruction with a flap and/or graft, were included. Results: Thirty-four studies, including 804 patients who received NPWT, were included. The partial/total flap loss rate was 6.95% (n = 9 studies), the infection rate was 19.5% (n = 25 studies), the nonunion rate was 18% (n = 15 studies), the delayed union rate was 9.31% (n = 3 studies), and the amputation rate was 15.4% (n = 6 studies). The mean late stay was 43.1 days (n = 9 studies), and the follow-up length was 23.7 months (n = 9 studies). The mean time to wound healing was 5.63 months (n = 2 studies), and the time to soft tissue coverage was 40.8 days (n = 12 studies). The mean time to achieve bone union was 7.26 months (n = 6 studies). Conclusion: NPWT can be used to temporize traumatic wounds while awaiting soft tissue reconstruction.
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Vascularized composite allotransplantation (VCA) is the transplantation of multiple tissues such as skin, muscle, bone, nerve, and vessels, as a functional unit (i.e., hand or face) to patients suffering from major tissue trauma and functional deficits. Though the surgical feasibility has been optimized, issues regarding graft rejection remains. VCA rejection involves a diverse population of cells but is primarily driven by both donor and recipient lymphocytes, antigen-presenting cells, macrophages, and other immune as well as donor-derived cells. In addition, it is commonly understood that different tissues within VCA, such as the skin, elicits a stronger rejection response. Currently, VCA recipients are required to follow potent and lifelong immunosuppressing regimens to maximize graft survival. This puts patients at risk for malignancies, opportunistic infections, and cancers, thereby posing a need for less perilous methods of inducing graft tolerance. This review will provide an overview of cell populations and mechanisms, specific tissue involved in VCA rejection, as well as an updated scope of current methods of tolerance induction.
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Breast cancer is a leading cause of cancer among cisgender women worldwide, with an incidence that continues to rise. Breast reconstruction is increasingly recognized as an integral part of breast cancer management. In tandem, the population of trans women is also increasing. However, few studies have focused on the management of breast cancer in this population, given that estrogen therapy has the potential to increase the risk of breast cancer. We present the case of a 51-year-old trans woman diagnosed with right breast cancer following a 32-year history of estrogen therapy. She presented to our clinic for consultation and immediate breast reconstruction. She opted for bilateral skin-sparing mastectomies, sentinel lymph node biopsies, and immediate breast reconstruction using deep inferior epigastric perforator free flaps. There were no postoperative flap complications. Final pathology revealed invasive mucinous carcinoma, devoid of lymph node involvement. The patient was satisfied with her reconstruction and is currently planning for nipple reconstruction. To the authors' knowledge, this is the first reported case in the literature of bilateral deep inferior epigastric perforator free flap reconstruction in the trans female population after breast cancer diagnosis. This case underscores the need for a holistic treatment approach and heightened vigilance among trans women on estrogen therapy. It also highlights that breast reconstruction should be considered and offered to this patient population.
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Tissue engineering predominantly relies on trial and error in vitro and ex vivo experiments to develop protocols and bioreactors to generate functional tissues. As an alternative, in silico methods have the potential to significantly reduce the timelines and costs of experimental programs for tissue engineering. In this paper, we propose a methodology to formulate, select, calibrate, and test mathematical models to predict cell population growth as a function of the biochemical environment and to design optimal experimental protocols for model inference of in silico model parameters. We systematically combine methods from the experimental design, mathematical statistics, and optimization literature to develop unique and explainable mathematical models for cell population dynamics. The proposed methodology is applied to the development of this first published model for a population of the airway-relevant bronchio-alveolar epithelial (BEAS-2B) cell line as a function of the concentration of metabolic-related biochemical substrates. The resulting model is a system of ordinary differential equations that predict the temporal dynamics of BEAS-2B cell populations as a function of the initial seeded cell population and the glucose, oxygen, and lactate concentrations in the growth media, using seven parameters rigorously inferred from optimally designed in vitro experiments.
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Proliferación Celular , Simulación por Computador , Pulmón , Modelos Biológicos , Humanos , Línea Celular , Pulmón/citología , Pulmón/metabolismo , Células Epiteliales/citología , Células Epiteliales/metabolismo , Ingeniería de Tejidos/métodos , Glucosa/metabolismo , Oxígeno/metabolismoRESUMEN
Balancing the immune response after solid organ transplantation (SOT) and vascularized composite allotransplantation (VCA) remains an ongoing clinical challenge. While immunosuppressants can effectively reduce acute rejection rates following transplant surgery, some patients still experience recurrent acute rejection episodes, which in turn may progress to chronic rejection. Furthermore, these immunosuppressive regimens are associated with an increased risk of malignancies and metabolic disorders. Despite significant advancements in the field, these IS related side effects persist as clinical hurdles, emphasizing the need for innovative therapeutic strategies to improve transplant survival and longevity. Cellular therapy, a novel therapeutic approach, has emerged as a potential pathway to promote immune tolerance while minimizing systemic side-effects of standard IS regiments. Various cell types, including chimeric antigen receptor T cells (CAR-T), mesenchymal stromal cells (MSCs), regulatory myeloid cells (RMCs) and regulatory T cells (Tregs), offer unique immunomodulatory properties that may help achieve improved outcomes in transplant patients. This review aims to elucidate the role of cellular therapies, particularly MSCs, T cells, Tregs, RMCs, macrophages, and dendritic cells in SOT and VCA. We explore the immunological features of each cell type, their capacity for immune regulation, and the prospective advantages and obstacles linked to their application in transplant patients. An in-depth outline of the current state of the technology may help SOT and VCA providers refine their perioperative treatment strategies while laying the foundation for further trials that investigate cellular therapeutics in transplantation surgery.
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Trasplante de Órganos , Humanos , Trasplante de Órganos/efectos adversos , Animales , Tratamiento Basado en Trasplante de Células y Tejidos/métodos , Rechazo de Injerto/inmunología , Rechazo de Injerto/prevención & control , InmunomodulaciónRESUMEN
Large volume soft tissue defects greatly impact patient quality of life and function while suitable repair options remain a challenge in reconstructive surgery. Engineered flaps could represent a clinically translatable option that may circumvent issues related to donor site morbidity and tissue availability. Herein, we describe the regeneration of vascularized porcine flaps, specifically of the omentum and tensor fascia lata (TFL) flaps, using a tissue engineering perfusion-decellularization and recellularization approach. Flaps were decellularized using a low concentration sodium dodecyl sulfate (SDS) detergent perfusion to generate an acellular scaffold with retained extracellular matrix (ECM) components while removing underlying cellular and nuclear contents. A perfusion-recellularization strategy allowed for seeding of acellular flaps with a co-culture of human umbilical vein endothelial cell (HUVEC) and mesenchymal stromal cells (MSC) onto the decellularized omentum and TFL flaps. Our recellularization technique demonstrated evidence of intravascular cell attachment, as well as markers of endothelial and mesenchymal phenotype. Altogether, our findings support the potential of using bioengineered porcine flaps as a novel, clinically-translatable strategy for future application in reconstructive surgery.
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Bioingeniería , Calidad de Vida , Humanos , Porcinos , Animales , Bioingeniería/métodos , Ingeniería Biomédica , Perfusión , Colgajos Quirúrgicos , Matriz Extracelular , Andamios del Tejido , Ingeniería de Tejidos/métodosRESUMEN
Adipose tissue (AT) is a large and important energy storage organ as well as an endocrine organ with a critical role in many processes. Additionally, AT is an enormous and easily accessible source of multipotent cell types used in our day for all types of tissue regeneration. The ability of adipose-derived stem cells (ADSCs) to differentiate into other types of cells, such as endothelial cells (ECs), vascular smooth muscle cells, or cardiomyocytes, is used in tissue engineering in order to promote/stimulate the process of angiogenesis. Being a key for future successful clinical applications, functional vascular networks in engineered tissue are targeted by numerous in vivo and ex vivo studies. The article reviews the angiogenic potential of ADSCs and explores their capacity in the field of tissue engineering (TE).
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Células Endoteliales , Ingeniería de Tejidos , Diferenciación Celular , Adipocitos/metabolismo , Tejido Adiposo/fisiología , Células Madre MultipotentesRESUMEN
A hallmark of plastic and reconstructive surgery is restoring form and function. Historically, tissue procured from healthy portions of a patient's body has been used to fill defects, but this is limited by tissue availability. Human-induced pluripotent stem cells (hiPSCs) are stem cells derived from the de-differentiation of mature somatic cells. hiPSCs are of particular interest in plastic surgery as they have the capacity to be re-differentiated into more mature cells, and cultured to grow tissues. This review aims to evaluate the applications of hiPSCs in the plastic surgery context, with a focus on recent advances and limitations. The use of hiPSCs and non-human iPSCs has been researched in the context of skin, nerve, vasculature, skeletal muscle, cartilage, and bone regeneration. hiPSCs offer a future for regenerated autologous skin grafts, flaps comprised of various tissue types, and whole functional units such as the face and limbs. Also, they can be used to model diseases affecting tissues of interest in plastic surgery, such as skin cancers, epidermolysis bullosa, and scleroderma. Tumorigenicity, immunogenicity and pragmatism still pose significant limitations. Further research is required to identify appropriate somatic origin and induction techniques to harness the epigenetic memory of hiPSCs or identify methods to manipulate epigenetic memory.
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Células Madre Pluripotentes Inducidas , Procedimientos de Cirugía Plástica , Cirugía Plástica , Humanos , Diferenciación Celular , PielRESUMEN
Objectives: Tissue engineering approaches via repopulation of acellular biological grafts provide an exciting opportunity to generate lung grafts for transplantation. Alveolar type 2 (AT2) cells are a promising cell source for re-epithelialization. There are however inherent limitations with respect to their survival and growth, thus impeding their usability for tissue engineering applications. This study investigates the use of mesenchymal stromal cells to support primary AT2 cells for recellularization of mouse lung scaffolds. Methods: AT2 cells and bone marrow-derived mesenchymal cells (BMC) were co-delivered to decellularized mouse lung scaffolds. Recellularized lungs were evaluated for cell surface coverage, viability, and differentiation at 1 and 4 days after cell seeding. Recellularization was evaluated via histological analysis and immunofluorescence. Results: Simultaneous delivery of AT2 and BMC into acellular lung scaffolds resulted in enhanced cell surface coverage and reduced AT2 cell apoptosis in the recellularized scaffolds at Day 1 but not Day 4. AT2 cell number decreased after 4 days in both of AT2 only and codelivery groups suggesting limited expansion potential in the scaffold. After retention in the scaffold, AT2 cells differentiated into Aqp5-expressing cells. Conclusions: Our results indicate that BMC support AT2 cell survival during the initial attachment and engraftment phase of recellularization. While our findings suggest only a short-term beneficial effect of BMC, our study demonstrates that AT2 cells can be delivered and retained in acellular lung scaffolds; thus with preconditioning and supporting cells, may be used for re-epithelialization. Selection and characterization of appropriate cell sources for use in recellularization, will be critical for ultimate clinical application.
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Biological scaffolds for airway reconstruction are an important clinical need and have been extensively investigated experimentally and clinically, but without uniform success. In this study, we evaluated the use of a decellularized bronchus graft for airway reconstruction. Decellularized left bronchi were procured from decellularized porcine lungs and utilized as grafts for airway patch transplantation. A tracheal window was created and the decellularized bronchus was transplanted into the defect in a porcine model. Animals were euthanized at 7 days, 1 month, and 2 months post-operatively. Histological analysis, immunohistochemistry, scanning electron microscopy, and strength tests were conducted in order to evaluate epithelialization, inflammation, and physical strength of the graft. All pigs recovered from general anesthesia and survived without airway obstruction until the planned euthanasia timepoint. Histological and electron microscopy analyses revealed that the decellularized bronchus graft was well integrated with native tissue and covered by an epithelial layer at 1 month. Immunostaining of the decellularized bronchus graft was positive for CD31 and no difference was observed with immune markers (CD3, CD11b, myeloperoxidase) at two months. Although not significant, tensile strength was decreased after one month, but recovered by two months. Decellularized bronchial grafts show promising results for airway patch reconstruction in a porcine model. Revascularization and re-epithelialization were observed and the immunological reaction was comparable with the autografts. This approach is clinically relevant and could potentially be utilized for future applications for tracheal replacement.
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Ingeniería de Tejidos , Andamios del Tejido , Porcinos , Animales , Ingeniería de Tejidos/métodos , Trasplante Autólogo , Bronquios , TráqueaRESUMEN
INTRODUCTION: Necrotizing fasciitis (NF) is a life-threatening infection and a surgical emergency. Not all clinicians have the experience or resources to detect NF in its early stages. OBJECTIVE: To develop a diagnostic algorithm for primary care and emergency physicians to identify patients with possible NF, including an initial approach to triaging such individuals. METHODS: Medline was searched to identify studies of validated algorithms for NF diagnosis and/or cohort or case series providing clinical and diagnostic features of NF. Candidate algorithms were validated via application to 3 published cases of initially misdiagnosed NF. We retrospectively reviewed NF cases between 2011 and 2022 at our center to validate our algorithm. RESULTS: The search yielded 540 articles; 109 were included following a review of abstracts. No published validated diagnostic algorithm was identified. Using the reported clinical and diagnostic features of NF, we generated an algorithm of the "3Ds" of NF: Disproportionate pain, Dermatological findings, and Disorganized physiology. A larger number of Ds indicated a greater level of suspicion for NF and prioritization for urgent surgical consultation. In 3 published cases of missed NF, the 3Ds algorithm successfully identified all as having possible NF. On reviewing our cases, we identified 56 patients with NF during an 11 year period. 66% of whom had the 3Ds at their initial presentation. DISCUSSION: The 3Ds algorithm, a simple and easy-to-remember tool can be easily applied in a primary or emergency care setting, and may improve the early diagnosis of NF. Retrospective analysis of NF cases allows for validation of this algorithm. However, this algorithm requires prospective validation.
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Servicios Médicos de Urgencia , Fascitis Necrotizante , Humanos , Diagnóstico Precoz , Fascitis Necrotizante/diagnóstico , Fascitis Necrotizante/cirugía , Estudios Retrospectivos , TriajeRESUMEN
INTRODUCTION: Vasopressors are traditionally avoided in microsurgery due to concerns about their effect on free flap survival. We examine the impact of intraoperative vasopressors on microsurgical outcomes in a large series of DIEP flap breast reconstructions. METHODS: A retrospective chart review was performed of patients who underwent DIEP breast reconstruction between January 2010 and May 2020. Intraoperative and postoperative microsurgical outcomes were compared in patients who received vasopressors and those who did not. RESULTS: The study included 1102 women who underwent 1729 DIEP. 878 patients (79.7%) received intraoperative phenylephrine, ephedrine, or a combination of both. There was no significant difference in overall complications, intraoperative microvascular events, takebacks for microvascular complications, or partial or total flap loss between groups. Outcomes were not affected by vasopressor type, dose, or timing of administration. The vasopressor group received significantly lower intraoperative fluid volumes. Multivariate logistic regression found a significant association between overall complications and excessive fluids (OR 2.03, 99% CI 0.98-5.18, p = 0.03) but not vasopressor use (OR 0.79, 99% CI 0.64-3.16, p = 0.7) CONCLUSION: This study demonstrates that vasopressors do not adversely affect clinical outcomes after DIEP breast reconstruction. Withholding vasopressors results in excessive intravenous fluid administration and increased postoperative complications.
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Neoplasias de la Mama , Mamoplastia , Colgajo Perforante , Humanos , Femenino , Mastectomía/efectos adversos , Mastectomía/métodos , Estudios Retrospectivos , Neoplasias de la Mama/tratamiento farmacológico , Mamoplastia/efectos adversos , Mamoplastia/métodos , Vasoconstrictores , Complicaciones Posoperatorias/etiología , Colgajo Perforante/cirugíaRESUMEN
PURPOSE: To elicit a patient-prioritized agenda and preferences for upper extremity lymphedema (LE) research. METHODS: Focus group sessions (FGs) were conducted with English-speaking, adult women (18 years and older) with breast cancer-related LE (BCRL) seeking conservative or surgical care at two tertiary cancer centers in Ontario, Canada. An interview guide was used; women were asked to describe health-related quality of life (HRQL) outcomes that mattered the most to them, followed by their preferences for research study design and for providing patient-reported outcomes measure (PROM) data. Inductive content analysis was used to identify themes and subthemes. RESULTS: A total of 16 women participated in 4 FG sessions (55 ± 9.5 years) and described the impact of LE on their appearance, physical, psychosocial, and sexual well-being. Women emphasized that psychosocial well-being was often not discussed in clinical care and that they were poorly informed of LE risk and care options. Most women said that they would not be willing to be randomized to surgical versus conservative management of LE. They also expressed a preference to complete PROM data electronically. All women emphasized the value of having an open text option alongside PROMs to expand on their concerns. CONCLUSION: Patient centeredness is key to generating meaningful data and ensuring ongoing engagement in clinical research. In LE, comprehensive PROMs that measure a range of HRQL concerns, especially psychosocial well-being, should be considered. Women with BCRL are reluctant to be randomized to conservative care when a surgical option is available, resulting in implications for planning trial sample size and recruitment.
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Neoplasias de la Mama , Linfedema , Adulto , Femenino , Humanos , Neoplasias de la Mama/complicaciones , Neoplasias de la Mama/cirugía , Escisión del Ganglio Linfático , Linfedema/cirugía , Ontario , Calidad de Vida , Extremidad Superior , Persona de Mediana EdadRESUMEN
Acute rejection in vascularized composite allotransplantation has been identified using the Banff 2007 working classification. We propose an addition to this classification based on histological and immunological assessment within the skin and subcutaneous tissue. Methods: Biopsies from vascularized composite transplant patients were obtained at scheduled visits and whenever skin changes occurred. Histology and immunohistochemistry were performed on all samples, looking at infiltrating cells. Results: Observations were made specifically related to each component of the skin, including the epidermis, dermis, vessels, and subcutaneous tissue. Our findings led to the establishment of the University Health Network addition of skin rejection. Conclusions: The high rate of rejection where the skin is involved requires novel techniques for early detection. The University Health Network skin rejection addition can serve as an adjunct to the Banff classification.
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The applications of Vascularized composite allotransplantation (VCA) are increasing since the first successful hand transplantation in 1998. However, the abundance of muscle tissue makes VCA's vulnerable to ischemia-reperfusion injury (IRI), which has detrimental effects on the outcome of the procedure, restricting allowable donor-to-recipient time and limiting its widespread use. The current clinical method is Static cold storage (SCS) and this allows only 6â h before irreversible damage occurs upon reperfusion. In order to overcome this obstacle, the focus of research has been shifted towards the prospect of ex-vivo perfusion preservation which already has an established clinical role in solid organ transplants especially in the last decade. In this comprehensive qualitative review, we compile the literature on all VCA machine perfusion models and we aim to highlight the essentials of an ex vivo perfusion set-up, the different strategies, and their associated outcomes.
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Vascularized composite allotransplantation is becoming the emerging standard for reconstructive surgery treatment for patients with limb trauma and facial injuries involving soft tissue loss. Due to the complex immunogenicity of composite grafts, patients who undergo vascularized composite allotransplantation are reliant on lifelong immunosuppressive therapy. Decellularization of donor grafts to create an extracellular matrix bio-scaffold provides an immunomodulatory graft that preserves the structural and bioactive function of the extracellular matrix. Retention of extracellular matrix proteins, growth factors, and signaling cascades allow for cell adhesion, migration, proliferation, and tissue regeneration. Perfusion decellularization of detergents through the graft vasculature allows for increased regent access to all tissue layers, and removal of cellular debris through the venous system. Grafts can subsequently be repopulated with appropriate cells through the vasculature to facilitate tissue regeneration. The present work reviews methods of decellularization, process parameters, evaluation of adequate cellular and nuclear removal, successful applications of perfusion decellularization for use in vascularized composite allotransplantation, and current limitations.
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Large volume soft tissue defects lead to functional deficits and can greatly impact the patient's quality of life. Although surgical reconstruction can be performed using autologous free flap transfer or vascularized composite allotransplantation (VCA), such methods also have disadvantages. Issues such as donor site morbidity and tissue availability limit autologous free flap transfer, while immunosuppression is a significant limitation of VCA. Engineered tissues in reconstructive surgery using decellularization/recellularization methods represent a possible solution. Decellularized tissues are generated using methods that remove native cellular material while preserving the underlying extracellular matrix (ECM) microarchitecture. These acellular scaffolds can then be subsequently recellularized with recipient-specific cells. This protocol details the procurement and decellularization methods used to achieve acellular scaffolds in a pig model. In addition, it also provides a description of the perfusion bioreactor design and setup. The flaps include the porcine omentum, tensor fascia lata, and the radial forearm. Decellularization is performed via ex vivo perfusion of low concentration sodium dodecyl sulfate (SDS) detergent followed by DNase enzyme treatment and peracetic acid sterilization in a customized perfusion bioreactor. Successful tissue decellularization is characterized by a white-opaque appearance of flaps macroscopically. Acellular flaps show the absence of nuclei on histological staining and a significant reduction in DNA content. This protocol can be used efficiently to generate decellularized soft tissue scaffolds with preserved ECM and vascular microarchitecture. Such scaffolds can be used in subsequent recellularization studies and have the potential for clinical translation in reconstructive surgery.
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Calidad de Vida , Andamios del Tejido , Animales , Reactores Biológicos , Matriz Extracelular , Perfusión , Porcinos , Ingeniería de Tejidos/métodosRESUMEN
Traumatic injuries or cancer resection resulting in large volumetric soft tissue loss requires surgical reconstruction. Vascular composite allotransplantation (VCA) is an emerging reconstructive option that transfers multiple, complex tissues as a whole subunit from donor to recipient. Although promising, VCA is limited due to side effects of immunosuppression. Tissue-engineered scaffolds obtained by decellularization and recellularization hold great promise. Decellularization is a process that removes cellular materials while preserving the extracellular matrix architecture. Subsequent recellularization of these acellular scaffolds with recipient-specific cells can help circumvent adverse immune-mediated host responses and allow transplantation of allografts by reducing and possibly eliminating the need for immunosuppression. Recellularization of acellular tissue scaffolds is a technique that was first investigated and reported in whole organs. More recently, work has been performed to apply this technique to VCA. Additional work is needed to address barriers associated with tissue recellularization such as: cell type selection, cell distribution, and functionalization of the vasculature and musculature. These factors ultimately contribute to achieving tissue integration and viability following allotransplantation. The present work will review the current state-of-the-art in soft tissue scaffolds with specific emphasis on recellularization techniques. We will discuss biological and engineering process considerations, technical and scientific challenges, and the potential clinical impact of this technology to advance the field of VCA and reconstructive surgery.