Intestinal Peyer’s Patches: Structure, Function, and In Vitro Modeling

METHODS@#In this review, we summarize the unique structure and function of intestinal PPs and current technologies to establish in vitro intestinal PP system focusing on M cell within the follicle-associated epithelium and IgA+ B cell models for studying mucosal immune networks. Furthermore, multidisciplinary approaches to establish more physiologically relevant PP model were proposed. @*RESULTS@#PPs are surrounded by follicle-associated epithelium containing microfold (M) cells, which serve as special gateways for luminal antigen transport across the gut epithelium. The transported antigens are processed by immune cells within PPs and then, antigen-specific mucosal immune response or mucosal tolerance is initiated, depending on the response of underlying mucosal immune cells. So far, there is no high fidelity (patho)physiological model of PPs; however, there have been several efforts to recapitulate the key steps of mucosal immunity in PPs such as antigen transport through M cells and mucosal IgA responses. @*CONCLUSION@#Current in vitro PP models are not sufficient to recapitulate how mucosal immune system works in PPs. Advanced three-dimensional cell culture technologies would enable to recapitulate the function of PPs, and bridge the gap between animal models and human.

The Prevalence and Incidence of Insomnia in Korea during 2005 to 2013

Objective@#The aim of this study was to estimate the progress of insomnia prevalence and incidence over the past several years. Also, this study compared survival rates between individuals with and without insomnia. @*Methods@#The National Health Insurance Service-National Sample Cohort (NHIS-NSC) from 2002–2013 was used for this study. Prevalent cases of insomnia were defined using ICD-10 codes F51.0 or G47.0, or a prescription of sedatives. Cox’s proportional hazard analysis was conducted to compare survival rates between insomnia patients and people without insomnia. @*Results@#In 2013, there were 46,167 (5.78%) insomnia patients over 20 years old in this cohort. Insomnia was more common among women and the elderly. Annual incidence over the past several years remained steady but the prevalence increased. The survival of insomnia patients was lower than that of people without insomnia, and the hazard ratio for overall mortality was 1.702 (p<0.001). @*Conclusion@#This large-scale population-based cohort study provided current epidemiologic indicators of insomnia in the Korean general population.

Sleep Assessment During Shift Work in Korean Firefighters: A Cross-Sectional Study

BACKGROUND: This cross-sectional study assessed the sleep quality using the ActiGraph and investigated the relationship between the parameters of sleep assessment and the type of shift work in Korean firefighters. METHODS: The participants were 359 firefighters: 65 day workers (control group) and 294 shift workers (shift work group: 77 firefighters with 3-day shift, 72 firefighters with 6-day shift, 65 firefighters with 9-day shift, and 80 firefighters with 21-day shift). Sleep assessments were performed using the ActiGraph (wGT3X-BT) for 24 hours during day shift (control and shift work group) and night shift and rest day (shift work group). The participants recorded bed time and sleep hours during the measurement period. RESULTS: Sleep efficiency, total sleep time, and percentage of wake after sleep onset during night work were lower in the shift work group than control group (p < 0.05). Sleep efficiency decreased in night shift and increased in rest day, whereas wake after sleep onset increased in night shift and decreased in rest day (p < 0.05). Among shift work groups, sleep efficiency of 6-day shift was higher in day shift, and sleep efficiency of 21-day shift was lower in night shift than other shift groups (p < 0.05). CONCLUSION: We found that the sleep quality in night shift of the shift work group was poorer than the control group. As to the type of shift work, sleep quality was good in 6-day shift and poor in 21-day shift. Thus, fast rotating shift such as 6-day shift may be recommended to improve the sleep quality of the firefighters.

Estimating Lifetime Duration of Diabetes by Age and Gender in the Korean Population Using a Markov Model

BACKGROUND@#Duration of type 2 diabetes is clinically important. Duration of morbidity is an independent and critical predictor of developing its complications. This study aims to explore an applicability of a Markov model to estimate the duration of diabetes in the Korean population.@*METHODS@#We constructed the Markov model with two Markov states, diabetes and death, for estimation of duration of diabetes. The cycle of the Markov model was 1 year. Each diabetes onset by 5 years was considered from 30 to 85 years old or above. The endpoint of the Markov was 100 years old. Type 2 diabetes was operationally defined using the 10th revision of International Statistical Classification of Diseases and prescriptions of anti-diabetic drugs from the National Health Insurance Services-National Sample cohort. In each incident and existing prevalence cases, survival probabilities were obtained. Durations of diabetes from the Markov model were compared with those from the DisMod II program. Reductions of life expectancy due to diabetes were defined as differences of life expectancies between diabetic patients and the general public. Sensitivity analyses were also conducted using a cure rate and 95% confidence interval of survival probability.@*RESULTS@#The duration of diabetes gradually decreased with incident age in both genders. In the early 30s, the duration was the largest at 48.9 and 41.9 years in women and men, respectively. In the average incident age group of type 2 diabetes, the late 50s, the reduction of life expectancy due to diabetes was estimated to be about two years in both genders. As annual cure probabilities increased, the durations of diabetes were reduced.@*CONCLUSION@#This study estimated the duration of diabetes using a Markov model. The model seems to work well and diabetes could reduce life expectancy by about 2 years on average. This approach could be useful to estimate the duration of illness, calculate disability-adjusted life years, and conduct economic evaluation studies on interventions for diabetic patients.

Alginate-Catechol Cross-Linking Interferes with Insulin Secretion Capacity in Isolated Murine Islet Cells

Over the past three decades, human pancreatic islet isolation and transplantation techniques have developed as a routine clinical procedure for selected patients with type 1 diabetes mellitus. However, due to the donor shortage and required chronic systemic immunosuppression, the widespread application of islet transplantation is limited. To overcome these limitations, providing a physical barrier to transplanted islet cells with encapsulating biomaterial has emerged as a promising approach to enhance engraftment and promote islet survival post-transplantation. Alginate has been considered to be a reliable biomaterial, as it enhances islet survival and does not hamper hormone secretion. Alginate-catechol (Al-CA) hydrogel was reported to provide high mechanical strength and chemical stability without deformation over a wide range of pH values. In this study, we, demonstrated, for the first time in the literature, that encapsulation of murine pancreatic islet cells with Al-CA hydrogel does not induce cytotoxicity ex vivo for an extended period; however, it does markedly abate glucose-stimulated insulin secretion. Catechol should not be considered as a constituent for alginate gelation for encapsulating islet cells in the application of islet transplantation.

Three-Directional Reconstruction of a Massive Perineal Defect after Wide Local Excision of Extramammary Paget's Disease

Extramammary Paget's disease (EMPD) is a rare, slow-growing intraepithelial malignancy that mainly involves the genital region, including the vulva, penis, scrotum, perianal, and periurethral areas. Although several treatment options exist, wide local excision with a safe margin is considered the treatment of choice. After resection of the lesion, it is often challenging to reconstruct the defect because defects in the perineal region require adequate volume for protection and are susceptible to infections, which is a particularly significant risk for large defects. We report a case of perivulvar EMPD that was reconstructed with three-directional local flaps after wide excision of the tumor. We covered the defect sequentially using the following 3 flaps: a gracilis myocutaneous flap from the left thigh, a bipedicled V-Y advancement flap from the lower abdomen, and an internal pudendal artery perforator-based island flap from the right buttock. To the best of our knowledge, this report is the first to describe a three-directional approach to extensive perivulvar reconstruction.

Biomimetic Polymer Scaffolds to Promote Stem Cell-Mediated Osteogenesis

Bone tissue engineering using stem cells with osteogenic potential is a promising avenue of research for bone defect reconstruction. Organic, inorganic, and composite scaffolds have all been engineered to provide biomimetic microenvironments for stem cells. These scaffolds are designed to promote stem cell osteogenesis. Here, we review current technologies for developing biomimetic, osteoinductive scaffolds for stem cell applications. We summarize the reported in vitro and in vivo osteogenic effects of these scaffolds on stem cells.

Engineering Biomaterials for Feeder-Free Maintenance of Human Pluripotent Stem Cells

Human pluripotent stem cells (hPSCs) are capable of differentiating into any type of somatic cell, a characteristic that imparts significant therapeutic potential. Human embryonic stem cells and induced pluripotent stem cells are types of hPSCs. Although hPSCs have high therapeutic potential, their clinical relevance is limited by the requirement for animal feeder layers, which maintain their pluripotency and self-renewal. hPSCs grown on animal feeder cells are at high risk for pathogen contamination and can be affected by the immunogenicity of the feeder layer. The presence of animal feeder cells also limits the scalability of hPSCs in culture because of the high cost of culturing and batch-to-batch variations. Therefore, development of feeder-free systems is imperative for robust, lower-cost, xeno-free, scalable culture of hPSCs. Biomaterials engineered with bioactive molecules such as adhesion proteins and extracellular matrix proteins, or synthetic materials such as peptides and polymers, may provide alternative substrates to animal feeder cells. This article reviews biomaterial-based, feeder-free systems for hPSC growth and maintenance, which provide clinically relevant alternatives to feeder cell systems.

Tissue engineering of heart valves by recellularization of glutaraldehyde-fixed porcine valves using bone marrow-derived cells

To increase the biocompatibility and durability of glutaraldehyde (GA)-fixed valves, a biological coating with viable endothelial cells (ECs) has been proposed. However, stable EC layers have not been formed successfully on GA-fixed valves due to their inability to repopulate. In this study, to improve cellular adhesion and proliferation, the GA-fixed prostheses were detoxified by treatment with citric acid to remove free aldehyde groups. Canine bone marrow mononuclear cells (MNCs) were differentiated into EC-like cells and myofibroblast-like cells in vitro. Detoxified prostheses were seeded and recellularized with differentiated bone marrow-derived cells (BMCs) for seven days. Untreated GA-fixed prostheses were used as controls. Cell attachment, proliferation, metabolic activity, and viability were investigated and cell-seeded leaflets were histologically analyzed. On detoxified GA-fixed prostheses, BMC seeding resulted in uninhibited cell proliferation after seven days. In contrast, on untreated GA-fixed prostheses, cell attachment was poor and no viable cells were observed. Positive staining for smooth muscle a-actin, CD31, and proliferating cell nuclear antigen was observed on the luminal side of the detoxified valve leaflets, indicating differentiation and proliferation of the seeded BMCs. These results demonstrate that the treatment of GA-fixed valves with citric acid established a surface more suitable for cellular attachment and proliferation. Engineering heart valves by seeding detoxified GA-fixed biological valve prostheses with BMCs may increase biocompatibility and durability of the prostheses. This method could be utilized as a new approach for the restoration of heart valve structure and function in the treatment of end-stage heart valve disease.

Angiogenesis Induced by the Implantation of Autogenous Whole Bone Marrow Stem Cells in an Ischemic Animal Model

PURPOSE: Bone marrow contains many kinds of primitive cells and endothelial progenitor cells that secrete several growth factors. We hypothesized that angiogenesis could be induced by autogenous whole bone marrow stem cell implantation in an animal ischemic limb. METHOD: A chronic ischemic hind limb model was created by encircling the femoral artery with an ameroid constrictor (2 mm inner diameter) in a dog model. About 20 ml of autogenous whole bone marrow stem cells were aspirated from the femur and then injected into ischemic limb muscles. Contralateral limbs injected with 20 ml of normal saline as controls. To assess angiogenic effects, an angiogram and a histologic evaluation were performed at 8 weeks after bone marrow stem cell implantation. RESULT: Imaging analysis of angiograms showed that newly developed capillaries were significantly more plentiful in treated limbs. Mean capillary density in the treated limb group was significantly greater than that in the control group (151+/-11.7 vs 81.5+/-7.2 cap/mm2, respectively, P<0.05), and the proportion of larger diameter (Fig. 6) newly developed capillaries was significantly higher in treated limbs than in control limbs. CONCLUSION: These findings indicated that autogenous whole bone marrow stem cell implantation increases the efficiency of angiogenesis.

In Vivo Experiment of Tissue-Engineered Artificial Vessel / 대한흉부외과학회지

BACKGROUND: The number of patients with coronary artery disease and peripheral vascular disease are increasing, and the need of small diameter vessel is also increasing. We developed small diameter artificial vessel and experimented in vivo. MATERIAL AND METHOD: We got allogenic valve from mongrel dogs, and removed all cells from the allogenic valve. Then, we seeded autologous bone marrow cells onto the decellularized scaffold. After implantation of artificial vessel into the canine carotid artery, we performed angiography regularly. In case of vessel occlusion or at 8 weeks after operation, we euthanized dogs, and retrieved the implanted artificial vessels. RESULT: Control vessels were all occluded except one (which developed aneurysmal dilatation). But autologous cell seeded vascular graft were patent by 4 weeks in one, by 6 in one and by 8 weeks in two. Histologic examination of patent vessel revealed similar structure to native artery. CONCLUSION: Tissue-engineered vascular graft manufactured with decellularized allogenic matrix and autologous bone marrow cells showed that tissue engineered graft had similar structure to native artery.

Tissue Engineering of Vascular Graft Using Autogenous Bone Marrow Cell and Allogenous Acellular Vessel

PURPOSE: The objective of this study is to develop a tissue-engineered vascular graft using autologous bone marrow-derived cells (BMCs) and allogenous acellular vascular graft. METHOD: We developed a tissue- engineered vascular patch using autologous BMCs and allogenous acellularized tissue patches. The patches were implanted into the inferior vena cava of a canine in vivo model. Three weeks after implantation, the retrieved patches were investigated by histological and immunohistochemical analyses. RESULT: Cultured BMCs differentiated into endothelium-like and smooth muscle-like cells. The patch graft maintained patent for 3 weeks without any signs of thrombus formation. Histological, immunohistochemical, and scanning electron microscopic analyses of the retrieved patches revealed that new vascular tissues were successfully reconstructed within the patch matrices. CONCLUSION: The tissue-engineered vascular patch using autogenous BMCs and allogenous acellularized matrix maintained patent for 3 weeks and showed vascular tissues generation similar to native blood vessel. The findings of no thrombus and no aneurysmal formation in patch indicated good antithrombogenic property and mechanical property. This study demonstrates the feasibility of utilizing BMCs as an alternative cell source to reconstruct vascular tissues.

Development of a Tissue-Engineered Vascular Graft Using Autologous Bone Marrow-Derived Cells and Biodegradable Polymer Scaffold

PURPOSE: The objective of this study is to develop a tissue-engineered vascular graft using autologous bone marrow-derived cells (BMCs) and biodegradable polymer scaffold. METHOD: Autologous canine BMCs were isolated from bone marrow aspirate and cultured. A tubular scaffold was fabricated by immersing polyglycolic acid (PGA) sheet in poly (glycolide-co-caprolactone) (PGCL) solution and wrapping it around a cylindrical mold. The expanded BMCs were seeded onto the PGA/PGCL tubular scaffold (internal diameter: 7 mm, length: 35 mm) and further cultured in vitro for 1 week. The graft was anastomosed to the abdominal artery in a canine model. One week after implantation, the retrieved graft was investigated by histological and immunohistochemical analyses. RESULT: Cultured BMCs differentiated into endothelial-like and smooth muscle-like cells. The PGA tubular scaffold reinforced with PGCL was successfully implanted in an animal model without graft rupture. The vascular graft engineered with BMCs was occluded at 1 week after implantation due to thrombus formation. Histological and immunohistochemical analyses of the retrieved graft revealed that extracellular matrix proteins such as smooth muscle alpha-actin, smooth muscle myosin heavy chain and collagen were produced partially in the graft media. CoNCLUSION: The tissue-engineered vascular graft developed in this study led to graft failure due to early occlusion. Nevertheless, it is confirmed that the PGA/PGCL scaffold has microstructures appropriate for cell proliferation and good mechanical properties. This result suggests the possibile application of this scaffold as a material for engineering of diseased vascular tissues.