Repopulation Research Articles

“A comparative study using conventional concomitant chemoradiotherapy (using cisplatin-based chemotherapy) with accelerated (six fractions a week) chemoradiotherapy in inoperable or nonresectable locally advanced non-small cell lung cancers:” A prospective randomized trial

Context: The conventional concomitant chemoradiotherapy (CCRT) is the standard treatment for locally advanced non-small cell lung cancer. Accelerated CCRT results in shortening of overall treatment time which can contribute in controlling accelerated tumor repopulation. The increase in tumor control probability (TCP) can be expected with no or little effect on late normal tissue injury for a given total dose. Aim: The aim of this study was to compare the disease response, toxicity profile, quality of life (QoL), and overall survival in accelerated versus conventional CCRT. Subjects and Methods: Total 42 patients were randomized into two groups – study group (n = 21): Accelerated CCRT, radiation was given as 6 fractions per week (60 Gy/5 weeks/30#) with injection cisplatin 20 mg/m2 intravenous (iv) days 1–5 and days 29–33 + injection etoposide 50 mg/m2 iv days 1–5 and days 29–33 and control group (n = 21): Conventional CCRT, radiation was given as 5 fractions per week (60 Gy/6 weeks/30#) along with the same chemotherapy. External beam radiation therapy was delivered by cobalt-60 machines. Results: The overall response rate (complete and partial response) for all patients was 66.6%. In the control group, it was 66.2%, and in the study group, it was 66.6%. Grade ≥II pulmonary, hematological, and esophageal toxicities were seen in 57%, 43%, and 24% in patients of the control group and 53%, 53%, and 33% in the study group, respectively. In QoL analysis, maximum improvement was noted for hemoptysis, arm/shoulder pain, dyspnea, and chest pain in both the groups. Statistical Analysis Used: The data were analyzed by Student's t-test and Chi-square test. P

Observation of two threshold fields for runaway-electron generation in tokamaks

Two different threshold electric fields, characterizing a lower field required for significant seed RE generation and sustainment and a higher field required for the RE avalanche onset, have been experimentally observed in the flattop of EAST discharges. These results demonstrate that the threshold electric field for the RE avalanche onset is 1.2-fold higher than the RE detection onset field required for the primary generation. An updated 0-D model, including the delay in the RE avalanche onset, suggests that the RE population should be less than the previous prediction. The delay in the RE avalanche onset also opens a possibility for RE suppression at relatively low electron density.

Experimental diabetes negatively affects the spermatogonial stem cells' self-renewal by suppressing GDNF network interactions.

The present study was done to analyse the time-dependent effects of diabetes on Sertoli cells-spermatogonial stem cells' (SSCs) network interaction by focusing on glial cell line-derived neurotrophic factor (GDNF) and its special receptors, gfrα1 and c-RET as well as the Bcl-6b. In total, 40 Wistar rats were considered in; control, 20, 45 and 60days diabetes-induced groups. An experimental diabetes was induced by STZ. The GDNF, gfrα1, c-RET and Bcl-6b expressions were evaluated. The serum level of testosterone, tubular repopulation (RI) and spermiogenesis (SPI) indices, general histological alterations, germ cells, mRNA damage, sperm count and viability were assessed. The diabetes, in a time-dependent manner, diminished mRNA and protein levels of GDNF, gfrα1, c-RET and Bcl-6b versus control group (p<.05), enhanced percentage of seminiferous tubules with negative RI, SPI, and diminished Leydig and Sertoli cells distribution, serum levels of testosterone, sperm count and viability. Finally, the number, percentage of cells and seminiferous tubules with normal mRNA content were significantly (p<.05) diminished. In conclusion, as a new data, we showed that the diabetes by inducing severe mRNA damage and suppressing GDNF, gfrα1, c-RET and Bcl-6b expressions, potentially affects the Sertoli-SSCs' network and consequently inhibits the SSCs' self-renewal process.

Hematopoietic Stem Cells

The small population of pluripotent hematopoietic stem cells (PHSCs) in the bone marrow consists of short-term reconstituting cells (STRCs) and long-term reconstituting cells (LTRCs), based on how quickly the transplanted cells can produce progeny in an irradiated recipient. They can be “purified” using a combination of cell size; density; fluorescent dye uptake; resistance to cytotoxic chemicals; and cell-surface markers including Thy 1.1 (T), Sca-1 (S), c-kit (K), lineage (L), CD38 (38), and CD34 (34). Using five-color fluorescence-activated cell sorting the long term, very primitive mouse LTRCs are L-/lo, S+, K+, 38+, 34-, and appear to mature to L-/lo, S+, K+, 38+, 34+ cells and then to L-/lo, S+, K+, 38-, 34+; thus, STRCs acquire CD34 and lose CD38 on maturation from CD34- LTRCs. CD34 has been used to isolate PHSCs for human transplantation studies; therefore, the LTRC may be lost during this procedure. Experimental transplantation studies indicate that the best reconstitution occurs when both cell populations are present, the more mature cells activating the immature cells after myeloablation, whereas the mature cells provide negative control in normal animals. Functionally the type of assay that has been most widely used for the quantitation of mouse stem cells is the in vivo repopulating assay. Different numbers of donor cells are combined with a standard number of normal bone marrow cells. The normal cells protect against the immediate effects of myeloablation and compete with the donor stem cells. The proportions of mature cells derived from the donor stem cells are determined by the detection of a donor-specific marker, such as an isoenzyme, Y-chromosome, or congenic antigen. Similarly, using limiting dilution transplant of a donor test population of cells and a standard number of stem cell—compromised serially transplanted cells, the relative contribution of the donor cells is measured as a competitive repopulating unit. Finally, the repopulating stem cell unit assay using complete myeloablation and busulfan-treated bone marrow radioprotective support cells provides comparatively rapid and sensitive detection of the very small numbers of LTRCs present in limiting dilution transplants. This procedure utilizes busulfan because it appears preferentially stem cell toxic, and it provides radioprotective support cells that are unable to compete effectively with normal donor stem cells in the population under investigation. Stem cells are selected based on their ability to produce both lymphoid and myeloid repopulation in severely ablated mice, rather than competitive ability.

The 4Rs in radiation therapy

It has been realized that the 4Rs (repair, repopulation, redistribution, and reoxygenation) would affect the result of cell irradiation, and thus radiation treatment. The 4Rs each occurs at different dose rates, usually very low dose rates. Depending on the dose rate used for treatment, the corresponding R should be included in the linear－quadratic equation (LQ) and biological effective dose (BED) calculation. For low dose rate brachytherapy(LDR) especially permanent implant, all the 4Rs should be included in LQ for BED calculation. The 4Rs, especially repair and repopulation, play a critical role in dose fractionation. Various dose fractionation schemes such as hyperfractionation and hypofractionation are determined in consideration of the 4Rs. Stereotactic radiation therapy uses hypofractionation with high fractional doses and combine with high accuracy target localization techniques to achieve high local control rates compared to conventional dose fractionation schemes. The 4Rs have been taken into account for LDR and permanent implant. Recently, LQ for permanent implant brachytherapy has been modified to include all the 4Rs for gynecological malignancy 131Cs permanent implants. Including the 4Rs in radiation therapy has significantly improved the effectiveness and efficiency of radiation therapy for cancer treatment. Key words: Repair; Repopulation; Redistribution; Reoxygenation; Linear quadratic equation

The effects of kinetic instabilities on the electron cyclotron emission from runaway electrons

In this paper we show that the kinetic instabilities associated with runaway electron beams play an essential role for the production of high-level non-thermal electron–cyclotron-emission (ECE) radiation. Most of the non-thermal ECE comes from runaway electrons in the low-energy regime with large pitch angle, which are strongly scattered by the excited whistler waves. The power of ECE from runaway electrons is obtained using a synthetic diagnostic model based on the reciprocity method. The electron distribution function is calculated using a kinetic simulation model including the whistler wave instabilities and the quasilinear diffusion effects. Simulations based on DIII-D low-density discharge reproduces the rapid growth of the ECE signals observed in DIII-D experiments. Unlike the thermal ECE where radiation for a certain frequency is strongly localized inside the resonance region, the non-thermal ECE radiation from runaway electrons is nonlocal, and the emission-absorption ratio is higher than that of thermal electrons. The runaway electron tail is more significant for ECE with higher frequencies, and the ECE spectrum becomes flatter as RE population grows. The nonlinear behavior of the kinetic instabilities is illustrated in the oscillations of the ECE waves. The good agreement with the DIII-D experimental observations after including the kinetic instabilities clearly illustrate the significance of the scattering effects from wave-particle interactions, which can also be important for runaway electrons produced in disruptions.

The experimental study of endothelial progenitor cells in rat liver decellularized scaffold

Objective To engineer intact whole rat liver decellularized scaffolds and repopulated bone marrow-derived endothelial progenitor cells (EPCs) into the scaffolds by continous perfusion technology thus providing experimental support for the vasculation of decellularized liver scaffolds in liver engineering. Methods Decellularized liver scaffolds were obtained by perfusing method. The composition and structure was examed by hematoxylin-eosin staining (HE) and immunohistochemistry. Bone marrow derived EPCs were characterised by immunofluorescence of CD31, CD133 and Vascular endothelial growth factor (VEGF). EPCs were recellularized into the decellularized scaffolds by portal-vein infusion method and cultured by the dynamic circulation perfusion device. After cultivation, HE staining and immunofluorescence of CD31 were conducted to observe the growth situation of EPCs in the scaffolds. Results The rat decellulariezd liver scaffolds were successfully obtained by perfusion method. Histological staining demonstrated the remove of cellular component and the reservation of extracellular cell matrix. Immunohistochemistry staining demonstrated the retention of collagen I and laminin. The primary cultured EPCs were postive for CD31, CD133 and VEGF. The circulation perfusion device was composed of a peristaltic pump, oxygenator, chamber and the convey tubes. HE staining and immunofluorence revealed that EPCs can be located around the blood vessel wall. Conclusion The primary cultured EPCs can grew around the blood vessel wall of the decellularized liver scaffolds by circulation perfusion method. Key words: Liver; Decellularized scaffolds; Circulation perfusion culture; Vascularization

A non-coding RNA axis guides TGF-β-induced gemcitabine chemoresistance

The American Cancer Society estimates 79,030 new cases and 16,870 deaths from urinary bladder cancer (UBC) in the United States this year (1). UBC is prevalent in males and in fact is the 4 th most common cancer types in males (1). Besides sex, age is another risk factor for UBC with about 90% of cases reported in the age group of 55 and above. Depending on the stage of presentation, current treatment options for UBC patients include surgery, intravesical therapy, chemotherapy, radiation therapy and immunotherapy (2,3). Chemotherapy is inevitable for advanced-staged UBC patients besides being used as a neoadjuvant or adjuvant therapy in combination with surgery and radiation therapy. However, the most common drawback of chemotherapy in UBC patients is that it often leads to tumor relapse and recurrence. While numerous reasons can be attributed to such undesirable outcomes, the concept that a small fraction of tumor cells with cancer stem cell (CSC)-like properties are able to survive the harsh chemotherapeutic regimens and able to repopulate as drug resistant tumors has been around for nearly two decades (4,5). However, therapies aimed at eradicating CSCs as an effective therapeutic strategy are not available and remains as a key focus of cancer research.

Stress response mechanism in hematopoietic stem cells.

At steady state, hematopoietic stem cells(HSCs), the most undifferentiated cells in the hematological system, are kept quiescent in the cell cycle. Upon hematological stresses, including radiation, anti-cancer medication, infection, and transplantation, bone marrow HSCs enter the cell cycle and robustly repopulate the entire hematopoietic system via multi-lineage differentiation and self-renewal, partly due to the alteration of their surrounding microenvironment or niche. Such hematological repopulation activity is termed "stress hematopoiesis," an activity essential for homeostatic maintenance of blood production. Understanding stress hematopoiesis is also critical to establish efficient methods enabling expansion in vitro of HSCs, since forced activation of the cell cycle by cytokine supplementation induces a stress-like cellular state.

Replace, Revive, Repopulate

Replace, Revive, Repopulate

JoVE - Year in Review: 2015

In January 2015, JoVE Developmental Biology became the newest addition to the JoVE family, and featured a live-imaging protocol for visualizing the developing Drosophila eye. In February, JoVE Medicine showed state-of-the-art cranial ultrasound imaging in neonates. Advances in this technique have improved its diagnostic value, allowing timely therapeutic intervention. In March, JoVE Environment featured dendroecology, the science of using tree rings to study ecological effects of specific environmental factors. In April, JoVE Biology examined a mode of bacterial motility called swarming with a two-phase swarm assay. that can be used to study various aspects of bacterial growth. In May, JoVE Chemistry described the self-assembly of single-stranded DNA tiles into complex 2D shapes. This demonstrated the principles of DNA tiling as an approach for making programmable nanostructures. June 2015 marked the release of JoVE's 100th issue, and in JoVE Behavior, we featured protocols for assessing cognition, including a method of quantifying learning in young infants by tracking leg movements. In July, JoVE Medicine presented a method for measuring halitosis in dogs by taking breath samples, and performing gas chromatography. This assay could be used in trials of dog food formulated to fight bad breath in our canine companions. In August, JoVE Bioengineering contained a protocol for bioengineering kidney tissues. Kidneys are decellularized by perfusion, and repopulated with human renal cells, This promising technology can lead to kidney grafts made from a patient's own cells. In September, JoVE Environment examined herbicide resistance, which threatens commercial crop production. An excised leaf assay determines the rates of herbicide metabolism, which is useful for studying the metabolic basis of resistance. In October, JoVE Neuroscience featured a method for interfacing 3D neuronal cultures to micro-electrode arrays. The complex 3D assemblies closely approximate in vivo neural networks. November's edition of JoVE Behavior showcased the natural human ability to acquire new motor skills, which is central in a structured rehabilitation program for amputees as they learn how to use multifunctional prosthetics. In December, JoVE Immunology & Infection prepared us for the impending flu season with an easy protocol for sampling influenza in pigs. Because swine are important hosts for flu viruses, this method helps to monitor virus evolution and currently circulating strains. This Year in Review was just a sampling of more than 900 video-articles that JoVE published in 2015. Browse the JoVE archives for thousands of other videos, and come back each week to see brand-new material in JoVE: The Journal of Visualized Experiments.

High dose chemotherapy with stem cell support in the treatment of testicular cancer.

Testicular germ cell cancer (TGCC) is rare form of malignant disease that occurs mostly in young man between age 15 and 40. The worldwide incidence of TGCC is 1.5 per 100000 man with the highest rates in North Europe. After discovery of cisplatin cure rates of TGCC are very favorable between 90%-95% and unlike most solid tumors, cure rate for metastatic TGCC is around 80%. Metastatic TGCC is usually treated with 3-4 cycles of bleomycin, etoposide, cisplatinum chemotherapy with or without retroperitoneal surgery and cure rates with this approach are between 41% in poor risk group and 92% in good risk group of patients. Cure rates are lower in relapsed and refractory patients and many of them will die from the disease if not cured with first line chemotherapy. High dose chemotherapy (HDCT) approach was used for the first time during the 1980s. Progress in hematology allowed the possibility to keep autologous haematopoietic stem cells alive ex-vivo at very low temperatures and use them to repopulate the bone marrow after sub-lethal dose of intesive myeloablative chemotherapy. Despite the fact that there is no positive randomized study to prove HDCT concept, cure rates in relapsed TGCC are higher after high dose therapy then in historical controls in studies with conventional treatment. Here we review clinical studies in HDCT for TGCC, possibilities of mobilising sufficient number of stem cells and future directions in the treatment of this disease.

Paisajes prehispánicos Tardíos en San Juan Mayo (frontera Argentina - Bolivia)

Fil: Nielsen, Axel Emil. Consejo Nacional de Investigaciones Cientificas y Tecnicas; Argentina. Secretaria de Cultura de la Nacion. Direccion Nacional de Cultura y Museos. Instituto Nacional de Antropologia y Pensamiento Latinoamericano; Argentina

Accelerated repopulation in head and neck cancer.

Accelerated repopulation in head and neck cancer.

EP-1473: Modelling the impact of oxygenation, accelerated repopulation and heterogeneous fractionation on SBRT outcome

EP-1473: Modelling the impact of oxygenation, accelerated repopulation and heterogeneous fractionation on SBRT outcome

Effects of combined decellularization and cryopreservation procedures on morpho-functional properties of porcine aortic valve allografts

Heart valve disease is a major public health problem, with surgical valve replacement still representing the leading therapeutic option. In the last 20 years, implantation of cryopreserved human heart valves underwent so progressive increase that current availability of allogeneic valve substitutes is not sufficient to meet clinical demand. However, also valve allografts undergo long-term failure depending on host-versus-graft immune responses and degeneration of resident cells and extracellular matrix components with subsequent priming of mineralization processes. In a previous study, suitably decellularized porcine aortic valves implanted in the pulmonary position in Vietnamese pigs resulted to be permissive of in vivo spontaneous repopulation by recipient’s cells, showing tissue remodelling and satisfactory hemodynamic performance (1). Using the same animal model, decellularized valve allografts were compared with other ones which were additionally subjected to cryopreservation/thawing before implantation. Previous echocardiographic analysis showed near-normal hemodynamic behaviour for both allograft types. Here, microscopic examination revealed non-uniform outcomes for both treatments, because there was co-presence of native-like and altered regions. In the former, almost complete re-endothelialization and repopulation by cells with features of fibroblasts, myofibroblasts, and smooth muscle cells involved both cusps and aorta walls. Ultrastructural identification of typical canals of collagen fibrillogenesis and elastogenesis-related features revealed actual tissue remodelling to have been occurred. In aorta walls, incipient neo-vascularization and re-innervation of medial and adventitial tunicae were also detected. Conversely, altered regions showed fibrin deposits, inflammatory infiltrates, fragmented elastin fibers, and calcific loci in absence of cell repopulation, with these features mainly concerning cryopreserved allografts. In conclusion, cryopreservation was found to limit the favourable outcomes characterizing decellularized allografts, even if hemodynamic performance was not affected. However, both treatments were found to not compromise repopulation by host’s cells and tissue renewal. Thus, the obtained preclinical data suggest the feasibility to achieve cryobank-derived self-regenerating and hemodynamically functional allogeneic valve substitutes, after optimization of these two pre-implantation procedures or their mutual compatibility

Exploring a tissue engineering strategy as a novel approach for haemophilic arthropathy treatment

Among the most disabling complications of Haemophilia, repeated and sponta- neous intra-articular haemorrhages may cause irreversible damage to the joint. This leads to haemophilic arthropathy, a polyarticular disease characterized by joint stiff- ness, chronic pain and a severely limited range of motion. Occurrence of haemophilic arthropathy can be avoided by the prophylactic administration of clotting factors to prevent articular haemorrhages, but it can also be addressed using anti-inflammatory drugs and surgery to alleviate the effects of articular damage, up to arthroplasty as resolute option [1]. However, innovative strategies for the prevention and treatment of this common and serious complication are still required, due to some important limits of current therapies, first of all inhibitor development. In this work, we inves- tigated a tissue engineering approach to regenerate articular focal lesions in Haemo- philic patients by in vitro development of an autologous bio-hybrid prosthesis. For this purpose, we isolated articular chondrocytes from Haemophilic patients (HaeCs) and characterized them for the first time in literature, to verify whether they were altered by blood exposure. Using healthy chondrocytes as control, optical microscope morphological analysis, flow cytometry immunophenotype evaluation and gene expression study by qRT-PCR were performed. After that, an innovative compos- ite scaffold was obtained by combining decellularized Wharton’s Jelly (W’s J) from human umbilical cord with a novel biodegradable polyvinyl alcohol (PVA) hydrogel [2]. Finally, we assessed HaeCs capacity to re-populate biosynthetic scaffolds by Scan- ning Electron Microscopy and MTT assay on cells seeded on supports. Taken togeth- er, our results contributed to define HaeCs phenotype, highlighting the possibility to use these cells for autologous implant. What is more, HaeCs capacity to growth and proliferate on composite scaffolds set the stage for planning the development of autologous tissue substitutes for haemophilic cartilage regeneration.

Caracterización genética de Ichthyoelephas longirostris de los ríos La Miel y Ranchería usando marcadores microsatelites

El Ichthyoelephas longirostris comúnmente conocido como el Pataló es una especie endémica de la cuenca del río Magdalena y del río Ranchería. Posee una fuerte presión pesquera comercial y de consumo. Según el libro rojo de peces dulceacuícolas de Colombia actualmente se encuentra reportada como una especie amenazada debido a las fuertes alteraciones de su hábitat producidas principalmente por contaminación y erosión. Teniendo en cuenta su importancia y la falta de información genética reportada, en este estudio se analizaron seis marcadores microsatélites para determinar el grado de variabilidad y estructura genético-poblacional del Pataló de los ríos La Miel y Ranchería. Para las dos localidades la heterozigosidad esperada varió de 0,6182 a 0,546, la heterozigosidad observada entre 0,6812 a 0,454, la riqueza alélica entre 6,760 y 4,640 y la diversidad génica encontrada estuvo entre 0,631 y 0,540 respectivamente. El índice de endogamia FIS evidenció un exceso de heterocigotos dado por su valor medio negativo. Los análisis realizados indican que existen dos poblaciones diferentes de Pataló con una estructuración genética moderada, las cuales presentan un buen estado genético. Estos resultados son de gran valor por ser el primer estudio de caracterización genética realizado en esta especie y con el cual se podrán tomar medidas de control y manejo especialmente cuando ya se están implementando acciones de repoblamiento y se está trabajando en su reproducción en cautiverio.

Repopulation

Repopulation

Mesenchymal stem cells: potential application in intervertebral disc regeneration.

Chronic low back pain is one of the leading public health problems in developed countries. Degeneration of the intervertebral disc (IVD) is a major pathological process implicated in low back pain, which is characterized by cellular apoptosis and senescence with reduced synthesis of extracellular matrix (ECM). Currently, there is no clinical therapy targeting the reversal of disc degeneration. Recent advances in cellular and molecular biology have provided an exciting approach to disc regeneration that focuses on the delivery of viable cells to the degenerative disc. Adult mesenchymal stem cells (MSCs) are multipotent stem cells with self-renewal capacities and are able to differentiate into diverse specialized cell types, including chondrocyte lineages. The potential of stem cell therapy in disc degeneration is to repopulate the disc with viable cells capable of producing the ECM and restoring damaged tissue. The present literature review summarizes recent advances in basic research and clinical trials of MSCs to provide an outline of the key roles of MSCs therapies in disc repair. The review also discusses the controversies, challenges and therapeutic concepts for the future.