Embryonic stem cells develop into hepatocytes after intrasplenic transplantation in CCl_4-treated mice

AIM： To transplant undifferentiated embryonic stem （ES） cells into the spleens of carbon tetrachloride （CCl4）-treated mice to determine their ability to differentiate into hepatocytes in the liver. METHODS： CCh, 0.5 mL/kg body weight, was injected into the peritoneum of C57BL/6 mice twice a week for 5 wk. In group 1 （n = 12）, 1 × 10^5 undifferentiated ES cells （0.1 mL of 1 × 10^6/mL solution）, genetically labeled with GFP, were transplanted into the spleens 1 d after the second injection. Group 2 mice （n = 12） were injected with 0.2 mL of saline twice a week, instead of CCh, and the same amount of ES cells was transplanted into the spleens. Group 3 mice （n = 6） were treated with CCh and injected with 0.1 mL of saline into the spleen, instead of ES cells. Histochemical analyses of the livers were performed on post-transplantation d （PD） 10, 20, and 30. RESULTS： Considerable numbers of GFP-immunopositive cells were found in the periportal regions in group 1 mice （CCh-treated） on PD 10, however, not in those untreated with CCh （group 2）. The GFP-positive cells were also immunopositive for albumin （ALB）, alpha-1 antitrypsin, cytokeratin 18, and hepatocyte nuclear factor 4 alpha on PD 20. Interestingly, most of the GFP-positive cells were immunopositive for DLK, a hepatoblast marker, on PD 10. Although very few ES-derived cells were demonstrated immunohistologically in the livers of group 1 mice on PD 30, improvements in liver fibrosis were observed. Unexpectedly, liver tumor formation was not observed in any of the mice that received ES cell transplantation during the experimental period CONCLUSION： Undifferentiated ES cells developed into hepatocyte-like cells with appropriate integration into tissue, without uncontrolled cell growth.

Pluripotent Embryonic Stem Cells Developed into Medulloepithelioma in Nude Mice Eyes

Purpose: The pluripotent embryonic stem cells can differentiate into various kinds offormal tissues. There is no previous report on the differentiation of embryonic stem cellin the intraocular environment. In this paper, the authors tried to investigate theintraocular growth character of mice embryonic stem cells in nude mice.Methods: Murine embryonic stem cells were cultured and maintained in anundifferentiated state in vitro. They were transplanted into the right eyes of 20 nude miceby microinjection under operating microscope. Animal eye observation, light microscopeand immunohistochemical examinations were implemented.Results: Two to three days after transplantation, small pieces of gray-white materialcould be viewed in the vitreous cavity. Between the 15th and 20th day, the gray-whitemass grew into the anterior chamber in 4 nude mice eyes. Then, the mass at the anteriorchamber extended extraocularly. On the 30th day, a remarkable proptosis was observedin two of the four nude mice. In 6 to 45 days, the mice were executed for morphologicalexamination which showed the following typical structures: (1) Undifferentiated cellswith prominent nucleolius. (2) Flexner-Wintersteiner-like rosettes. (3) Medulloepithe-lioma-like structure: the cells were arranged in sheets, cords, tubes, and cysts. (4) Large,spindle-or astrocyte-like cells. (5) Cartilage-like structure. Immunohistochemically, mostof the cells were highly positive in NSE staining and a few cells were moderately positivein GFAP staining.Conclusions: Both animal eye findings and morphologic examinations certificated thatthe transplanted embryonic stem cells could grow in the eyes of nude mice anddifferentiate into intraocular medulloepithelioma.

Stem cell transplantation for spinal cord injury： a meta-analysis of treatment effectiveness and safety

OBJECTIVE： The aim of this study was to evaluate the effectiveness and safety of stem cell transplantation for spinal cord injury（SCI）.DATA SOURCES： PubM ed, EMBASE, Cochrane, China National Knowledge Infrastructure, China Science and Technology Journal, Wanfang, and Sino Med databases were systematically searched by computer to select clinical randomized controlled trials using stem cell transplantation to treat SCI, published between each database initiation and July 2016. DATA SELECTION： Randomized controlled trials comparing stem cell transplantation with rehabilitation treatment for patients with SCI. Inclusion criteria：（1） Patients with SCI diagnosed according to the American Spinal Injury Association（ASIA） International standards for neurological classification of SCI;（2） patients with SCI who received only stem cell transplantation therapy or stem cell transplantation combined with rehabilitation therapy;（3） one or more of the following outcomes reported： outcomes concerning neurological function including sensory function and locomotor function, activities of daily living, urination functions, and severity of SCI or adverse effects. Studies comprising patients with complications, without full-text, and preclinical animal models were excluded. Quality of the included studies was evaluated using the Cochrane risk of bias assessment tool and Rev Man V5.3 software, provided by the Cochrane Collaboration, was used to perform statistical analysis. OUTCOME MEASURES： ASIA motor score, ASIA light touch score, ASIA pinprick score, ASIA impairment scale grading improvement rate, activities of daily living score, residual urine volume, and adverse events.RESULTS： Ten studies comprising 377 patients were included in the analysis and the overall risk of bias was relatively low level. Four studies did not detail how random sequences were generated, two studies did not clearly state the blinding outcome assessment, two studies lacked blinding outcome assessment, one study lacked follow-up information, and four studies carried out selective reporting. Compared with rehabilitation therapy, stem cell transplantation significantly increased the lower limb light touch score（odds ratio（OR） = 3.43, 95% confidence interval（CI）： 0.01 – 6.86, P = 0.05）, lower limb pinprick score（OR = 3.93, 95%CI： 0.74 – 7.12, P = 0.02）, ASI grading rate（relative risk（RR） = 2.95, 95%CI： 1.64 – 5.29, P = 0.0003）, and notably reduced residual urine volume（OR = –8.10, 95%CI： –15.09 to –1.10, P = 0.02）. However, stem cell transplantation did not significantly improve motor score（OR = 1.89, 95%CI： –0.25 to 4.03, P = 0.08） or activities of daily living score（OR = 1.12, 95%CI： –1.17 to 4.04, P = 0.45）. Furthermore, stem cell transplantation caused a high rate of mild adverse effects（RR = 14.49, 95%CI： 5.34 – 34.08, P 〈 0.00001）; however, these were alleviated in a short time. CONCLUSION： Stem cell transplantation was determined to be an efficient and safe treatment for SCI and simultaneously improved sensory and bladder functions. Although associated minor and temporary adverse effects were observed with transplanted stem cells, spinal cord repair and axon remyelination were apparent. More randomized controlled trials with larger sample sizes and longer follow-up times are needed to further validate the effectiveness of stem cell transplantation in the treatment of SCI.

Stem cell transplantation for treating Parkinson's disease Literature analysis based on the Web of Science

OBJECTIVE： To identify global research trends of stem cell transplantation for treating Parkinson＇s disease using a bibliometric analysis of the Web of Science. DATA RETRIEVAL： We performed a bibliometric analysis of data retrievals for stem cell transplantation for treating Parkinson＇s disease from 2002 to 2011 using the Web of Science. SELECTION CRITERIA： Inclusion criteria： （a） peer-reviewed articles on stem cell transplantation for treating Parkinson＇s disease which were published and indexed in the Web of Science; （b） type of articles： original research articles, reviews, meeting abstracts, proceedings papers, book chapters, editorial material and news items; （c） year of publication： 2002-2011. Exclusion criteria： （a） articles that required manual searching or telephone access; （b） we excluded documents that were not published in the public domain; （c） we excluded a number of corrected papers from the total number of articles. MAIN OUTCOME MEASURES： （1） Type of literature; （2） annual publication output; （3） distribution according to journals; （4） distribution according to subject areas; （5） distribution according to country; （6） distribution according to institution; （7） comparison of countries that published the most papers on stem cell transplantation from different cell sources for treating Parkinson＇s disease; （8） comparison of institutions that published the most papers on stem cell transplantation from different cell sources for treating Parkinson＇s disease in the Web of Science from 2002 to 2011; （9） comparison of studies on stem cell transplantation from different cell sources for treating Parkinson＇s disease RESULTS： In total, 1 062 studies on stem cell transplantation for treating Parkinson＇s disease appeared in the Web of Science from 2002 to 2011, almost one third of which were from American authors and institutes. The number of studies on stem cell transplantation for treating Parkinson＇s disease had gradually increased over the past 10 years. Papers on stem cell transplantation for treating Parkinson＇s disease appeared in journals such as Stem Cells and Experimental Neurology. Although the United States published more articles addressing neural stem cell and embryonic stem cell transplantation for treating Parkinson＇s disease, China ranked first for articles published on bone marrow mesenchymal stem cell transplantation for treating Parkinson＇s disease. CONCLUSION： From our analysis of the literature and research trends, we found that stem cell transplantation for treating Parkinson＇s disease may offer further benefits in regenerative medicine.

Application of magnetic resonance imaging for monitoring stem cell transplantation for the treatment of cerebral ischemia

OBJECTIVE： To identify global research trends in the application of MRI for monitoring stem cell transplantation using a bibliometric analysis of Web of Science. DATA RETRIEVAL： We performed a bibliometric analysis of studies relating to the application of MRI for detecting stem cell transplantation for the treatment of cerebral ischemia using papers in Web of Science published from 2002 to 2011. SELECTION CRITERIA： The inclusion criteria were： （a） peer-reviewed articles on the application of MRI for detecting transplanted stem cells published and indexed in Web of Science; （b） year of publication between 2002 and 2011. Exclusion criteria were： （a） articles that required manual searching or telephone access; （b） some corrected papers. MAIN OUTCOME MEASURES： （1） Annual publication output; （2） distribution according to journals; （3） distribution according to institution; （4） distribution according to country; （5） top cited authors over the last 10 years. RESULTS： A total of 1 498 studies related to the application of MRI for monitoring stem cell transplantation appeared in Web of Science from 2002 to 2011, almost half of which were derived from American authors and institutes. The number of studies on the application of MRI for detecting stem cell transplantation has gradually increased over the past 10 years. Most papers on this topic appeared in Magnetic Resonance in Medicine. CONCLUSION： This analysis suggests that few experimental studies have been investigated the use of MRI for tracking SPIO-labeled human umbilical cord blood-derived mesenchymal stem cells during the treatment of cerebral ischemia.

Stem cell transplantation for treating spinal cord injury A literature comparison between studies of stem cells obtained from various sources

OBJECTIVE： To identify global research trends of stem cell transplantation for treating spinal cord injury using a bibliometric analysis of the Web of Science. DATA RETRIEVAL： We performed a bibliometric analysis of data retrievals for stem cell transplantation for treating spinal cord injury from 2002 to 2011 using the Web of Science. SELECTION CRITERIA： Inclusion criteria： （a） peer-reviewed articles on stem cell transplantation for treating spinal cord injury that were published and indexed in the Web of Science; （b） type of articles： original research articles, reviews, meeting abstracts, proceedings papers, book chapters, editorial material, and news items; and （c） year of publication： 2002-2011. Exclusion criteria： （a） articles that required manual searching or telephone access; （b） documents that were not published in the public domain; and （c） a number of corrected papers from the total number of articles. MAIN OUTCOME MEASURES： （1） Annual publication output; （2） distribution according to country; （3） distribution according to institution; （4） distribution according to journals; （5） distribution according to funding agencies; and （6） top cited articles over the last 10 years. RESULTS： Bone marrow mesenchymal stem cells and embryonic stem cells have been widely used for treating spinal cord injury. In total, 191 studies of bone marrow mesenchymal stem cell transplantation and 236 studies of embryonic stem cell transplantation for treating spinal cord injury appeared in the Web of Science from 2002 to 2011, and almost half of which were derived from American or Japanese authors and institutes. The number of studies of stem cell transplantation for treating spinal cord injury has gradually increased over the past 10 years. Most papers on stem cell transplantation for treating spinal cord injury appeared in journals with a particular focus on stem cell research, such as Stem Cells and Cell Transplantation. Although umbilical cord blood stem cells and adipose-derived stem cells have been studied for treating spinal cord injury, the number of published papers was much smaller, with only 21 and 17 records, respectively, in the Web of Science. CONCLUSION： Based on our analysis of the literature and research trends, we found that stem cells transplantation obtained from various sources have been studied for treating spinal cord injury; however, it is difficult for researchers to reach a consensus on this theme.

Stem cell transplantation for treating stroke:status,trends and development

The developing approaches of thrombolytic therapy, endovascular treatment, neuroprotective therapy, and stem cell therapy have enabled breakthroughs in stroke treatment. In this study, we summarize and analyze trends and progress in stem cell transplantation for stroke treatment by retrieval of literature from Thomson Reuters Web of Science database, the NIH Clinical Trial Planning Grant Program, and Clinical Trials Registration Center in North America. In the last 10 years, there has been an increasing number of published articles on stem cell transplantation for stroke treatment. In particular, research from the USA and China has focused on stem cell transplantation. A total of 2,167 articles addressing stem cell transplantation for stroke treatment from 2004 to 2013 were retrieved from the Thomson Reuters Web of Science database. The ma- jority of these articles were from the USA （854, 39.4%）, with the journal Stroke publishing the most articles （145, 6.7%）. Of the published articles, 143 were funded by the National Institutes of Health （accounting for 6.6% of total publications）, and 91 by the National Natural Science Foundation of China. Between 2013 and 2014, the National Institutes of Health provided finan- cial support （$130 million subsidy） for 329 research projects on stroke therapy using stem cell transplantation. In 2014, 215 new projects were approved, receiving grants of up to $70,440,000. Ninety clinical trials focusing on stem cell transplantation for stroke were registered in the Clinical Trial Registration Center in North America, with 40 trials registered in the USA （ranked first place）. China had the maximum number of registered research or clinical trials （10 projects）.

Fetal stem cell transplantation: Past, present, and future

Since 1928, human fetal tissues and stem cells have been used worldwide to treat various conditions. Although the transplantation of the fetal midbrain substantia nigra and dopaminergic neurons in patients suffering from Parkinson's disease is particularly noteworthy, the history of other types of grafts, such as those of the fetal liver, thymus, and pancreas, should be addressed as there are many lessons to be learnt for future stem cell transplantation. This report describes previous practices and complications that led to current clinical trials of isolated fetal stem cells and embryonic stem(ES) cells. Moreover, strategies for transplantation are considered, with a particular focus on donor cells, cell processing, and the therapeutic cell niche, in addition to ethical issues associated with fetal origin. With the advent of autologous induced pluripotent stem cells and ES cells, clinical dependence on fetal transplantation is expected to gradually decline due to lasting ethical controversies, despite landmark achievements.

Human embryonic stem cell lines with ccr5-del32 allele conferring resistance to HIV

A 32bp deletion in the chemokine receptor 5 (CCR5) gene (CMKBR5) was shown to be linked to HIV resistance. Bone marrow transplantation from the homozygous CCR5-del32 donor to a CDC Stage 2 HIV-positive recipient was demonstrated to confer a HIV resistance, resulting in discontinuation of antiretroviral therapy. In search for an unlimited source of CCR5-del32 cells for transplantation purposes, we tested 137 human embryonic stem cell (hESC) lines from the Reproductive Genetics Institute’s hESC lines collection, and report here the finding of 12 hESC lines with the CCR5-del32 allele, one of which represents a unique partenogenetic ESC line containing two copies of this deletion and may be studied for utility in stem cell transplantation treatment of HIV.

New frontiers in retinal transplantation

New frontiers about retinal cell transplantation for retinal degenerative diseases start from the idea that acting on stem cells can help regenerate retinal layers and establish new synapses among retinal cells.Deficiency or alterations of synaptic input and neurotrophic factors result in trans-neuronal degeneration of the inner retinal cells.Thus,the disruption of photoreceptors takes place.However,even in advanced forms of retinal degeneration,a good percentage of the ganglion cells and the inner nuclear layer neurons remain intact.This phenomenon provides evidence for obtaining retinal circuitry through the transplantation of photoreceptors into the subretinal region.The eye is regarded as an optimal organ for cell transplantation because of its immunological privilege and the relatively small number of cells collaborating to carry out visual activities.The eyeball's immunological privilege,characterized by the suppression of delayed-type hypersensitivity responses in ocular tissues,is responsible for the low rate of graft rejection in transplant patients.The main discoveries highlight the capacity of embryonic stem cells(ESCs)and induced pluripotent stem cells to regenerate damaged retinal regions.Recent progress has shown significant enhancements in transplant procedures and results.The research also explores the ethical ramifications linked to the utilization of stem cells,emphasizing the ongoing issue surrounding ESCs.The analysis centers on recent breakthroughs,including the fabrication of three-dimensional retinal organoids and the innovation of scaffolding for cell transportation.Moreover,researchers are currently assessing the possibility of CRISPR and other advanced gene editing technologies to enhance the outcomes of retinal transplantation.The widespread use of universally recognized safe surgical and imaging methods enables retinal transplantation and monitoring of transplanted cell growth toward the correct location.Currently,most therapy approaches are in the first phases of development and necessitate further research,including both pre-clinical and clinical trials,to attain favorable visual results for individuals suffering from retinal degenerative illnesses.

Differentiation of embryonic stem cells in adult bone marrow

Embryonic stem cells （ESCs） are a potential source of generating transplantable hematopoietic stem and progenitor cells,which in turn can serve as ＂seed＂ cells for hematopoietic regeneration.In this study,we aimed to gauge the ability of mouse ESCs directly differentiating into hematopoietic cells in adult bone marrow （BM）.To this end,we first derived a new mouse ESC line that constitutively expressed the green fluorescent protein （GFP） and then injected the ESCs into syngeneic BM via intra-tibia.The progeny of the transplanted ESCs were then analyzed at different time points after transplantation.Notably,however,most injected ESCs differentiated into non-hematopoietic cells in the BM whereas only a minority of the cells acquired hematopoietic cell surface markers.This study provides a strategy for evaluating the differentiation potential of ESCs in the BM micro-environment,thereby having important implications for the physiological maintenance and potential therapeutic applications of ESCs.

A systematic review of progenitor survival and maturation in Parkinsonian models

Stem cell-based brain repair is a promising emergent therapy for Parkinson's disease based on years of foundational research using human fetal donors as a cell source.Unlike current therapeutic options for patients,this approach has the potential to provide longterm stem cell–derived reconstruction and restoration of the dopaminergic input to denervated regions of the brain allowing for restoration of certain functions to patients.The ultimate clinical success of stem cell–derived brain repair will depend on both the safety and efficacy of the approach and the latter is dependent on the ability of the transplanted cells to survive and differentiate into functional dopaminergic neurons in the Parkinsonian brain.Because the pre-clinical literature suggests that there is considerable variability in survival and differentiation between studies,the aim of this systematic review was to assess these parameters in human stem cell-derived dopaminergic progenitor transplant studies in animal models of Parkinson's disease.A defined systematic search of the PubMed database was completed to identify relevant studies published up to March 2024.After screening,76 articles were included in the analysis from which 178 separate transplant studies were identified.From these,graft survival could be assessed in 52 studies and differentiation in 129 studies.Overall,we found that graft survival ranged from<1% to 500% of cells transplanted,with a median of 51%of transplanted cells surviving in the brain;while dopaminergic differentiation of the cells ranged from 0% to 46% of cells transplanted with a median of 3%.This systematic review suggests that there is considerable scope for improvement in the differentiation of stem cell-derived dopaminergic progenitors to maximize the therapeutic potential of this approach for patients.

Properties and applications of embryonic stem cells

Mouse embryonic stem (ES) cells are pluripotent cells derived from the early embryo and can be propagated stably in undifferentiated state in vitro. They retain the ability to differentiate into all cell types found in the embryonic and adult body in vivo, and can be induced to differentiate into many cell types under appropriate culture conditions in vitro. Using these properties, people have set up various differentiated systems of many cell types and tissues in vitro. Through analysis of these systems, one can identify novel bioactive factors and reveal mechanisms of cell differentiation and organogenesis. ES cell-derived differentiated cells can also be applied to cell transplantation therapy. In addition, we summarized the features and potential applications of human ES cells.

Advances in human stem cell therapies:pre-clinical studies and the outlook for central nervous system regeneration

Cell transplantation has come to the forefront of regenerative medicine alongside the discovery and application of stem cells in both research and clinical settings.There are several types of stem cells currently being used for pre-clinical regenerative therapies,each with unique characteristics,benefits and limitations.This brief review will focus on recent basic science advancements made with embryonic stem cells and induced pluripotent stem cells.Both embryonic stem cells and induced pluripotent stem cells provide platforms for new neurons to replace dead and/or dying cells following injury.Due to their capacity for reprogramming and differentiation into any neuronal type,research in preclinical rodent models has shown that embryonic stem cells and induced pluripotent stem cells can integrate,survive and form connections in the nervous system similar to de novo cells.Going forward however,there are some limitations to consider with the use of either stem cell type.Ethically,embryonic stem cells are not an ideal source of cells,genetically,induced pluripotent stem cells are not ideal in terms of personalized treatment for those with certain genetic diseases the latter of which may guide regenerative medicine away from personalized stem cell based therapies and into optimized stem cell banks.Nonetheless,the potential of these stem cells in central nervous system regenerative therapy is only beginning to be appreciated.For example,through genetic modification,stem cells serve as ideal platforms to reintroduce missing or downregulated molecules into the nervous system to further induce regenerative growth.In this review,we highlight the limitations of stem cell based therapies whilst discussing some of the means of overcoming these limitations.

Application of stem cell-derived retinal pigmented epithelium in retinal degenerative diseases： present and future

As a constituent of blood-retinal barrier and retinal outer segment（ROS） scavenger, retinal pigmented epithelium（RPE） is fundamental to normal function of retina. Malfunctioning of RPE contributes to the onset and advance of retinal degenerative diseases. Up to date, RPE replacement therapy is the only possible method to completely reverse retinal degeneration. Transplantation of human RPE stem cell-derived RPE（h RPESC-RPE） has shown some good results in animal models. With promising results in terms of safety and visual improvement, human embryonic stem cell-derived RPE（h ESC-RPE） can be expected in clinical settings in the near future. Despite twists and turns, induced pluripotent stem cell-derived RPE（i PSC-RPE） is now being intensely investigated to overcome genetic and epigenetic instability. By far, only one patient has received i PSCRPE transplant, which is a hallmark of i PSC technology development. During follow-up, no major complications such as immunogenicity or tumorigenesis have been observed. Future trials should keep focusing on the safety of stem cell-derived RPE（SC-RPE） especially in long period, and better understanding of the nature of stem cell and the molecular events in the process to generate SC-RPE is necessary to the prosperity of SC-RPE clinical application.

Targeted migration and differentiation of engrafted neural precursor cells in amyloid β-treated hippocampus in rats

Objective To observe the migration and differentiation of the neural precursor cells （NPCs） that derived from murine embryonic stem cells （ESCs） when they were transplanted into amyloid β （Aβ）-treated rat hippocampus. Methods MESPU35, a murine ESC cell line that express the enhanced green fluorescent protein （EGFP）, was induced differentiation into nestin-positive NPCs by modified serum-free methods. The Aβ plaques and the differentiation of the grafted cells were observed by immunofluorescent staining. Results Comparing 16 weeks with 4 weeks post-transplantation, the migration distance increased about 5 times; the rate of migratory NPCs differentiating into glial fibrillary acidic protein （GFAP）-positive cells kept rising from （30.41 ± 1.45）% to （49.25± 1.23）%, and the rate of NPCs differentiating into neurofilament 200 （NF200） positive cells increased from （16.68±0.95）% to （27.94± 1.21）%. Meanwhile, the GFAP-positive cells targeting to the ipsilateral side of Aβ plaques increased from 60.2% to 81.3 %, while the NF200-positive cells increased from 61.3% to 84.1%. The migration distance had significant positive linear correlations to the neuronal differentiation rate （r = 0.991） and to the astrocytic differentiation rate （r = 0.953）. Conclusion Engrafted NPCs migrate targetedly to the Aβ injection site and differentiate into neurons and astrocytes.

Recent advances in stem cell research for the treatment of diabetes

The success achieved over the last decade with islet transplantation has intensified interest in treating diabetes,not only by cell transplantation,but also by stem cells.The formation of insulin-producing cells from pancreatic duct,acinar,and liver cells is an active area of investigation.Protocols for the in vitro differentiation of embryonic stem(ES)cells based on normal developmental processes,have generated insulin-producing cells,though at low efficiency and without full responsiveness to extracellular levels of glucose.Induced pluripotent stem cells,which have been generated from somatic cells by introducing Oct3/4,Sox2,Klf4,and c-Myc,and which are similar to ES cells in morphology,gene expression,epigenetic status and differentiation,can also differentiate into insulin-producing cells.Overexpression of embryonic transcription factors in stem cells could efficiently induce their differentiation into insulin-expressing cells. The purpose of this review is to demonstrate recent progress in the research for new sources ofβ-cells, and to discuss strategies for the treatment of diabetes.

Potential for a pluripotent adult stem cell treatment for acute radiation sickness

Accidental radiation exposure and the threat of deliberate radiation exposure have been in the news and are a public health concern. Experience with acute radiation sickness has been gathered from atomic blast survivors of Hiroshima and Nagasaki and from civilian nuclear accidents as well as experience gained during the development of radiation therapy for cancer. This paper reviews the medical treatment reports relevant to acute radiation sickness among the survivors of atomic weapons at Hiroshima and Nagasaki, among the victims of Chernobyl, and the two cases described so far from the Fukushima Dai-Ichi disaster. The data supporting the use of hematopoietic stem cell transplantation and the new efforts to expand stem cell populations ex vivo for infusion to treat bone marrow failure are reviewed. Hematopoietic stem cells derived from bone marrow or blood have a broad ability to repair and replace radiation induced damaged blood and immune cell production and may promote blood vessel formation and tissue repair. Additionally, a constituent of bone marrow-derived, adult pluripotent stem cells, very small embryonic like stem cells, are highly resistant to ioniz-ing radiation and appear capable of regenerating radiation damaged tissue including skin, gut and lung.

Present and future cell therapies for pancreatic beta cell replenishment

If only at a small scale,islet transplantation has successfully addressed what ought to be the primary endpoint of any cell therapy:the functional replenishment of damaged tissue in patients.After years of less-thanoptimal approaches to immunosuppression,recent advances consistently yield long-term graft survival rates comparable to those of whole pancreas transplantation.Limited organ availability is the main hurdle that stands in the way of the widespread clinical utilization of this pioneering intervention.Progress in stem cell research over the past decade,coupled with our decades-long experience with islet transplantation,is shaping the future of cell therapies for the treatment of diabetes.Here we review the most promising avenues of research aimed at generating an inexhaustible supply of insulin-producing cells for islet regeneration,including the differentiation of pluripotent and multipotent stem cells of embryonic and adult origin along the beta cell lineage and the direct reprogramming of non-endocrine tissues into insulin-producing cells.

Cell therapy from bench to bedside:Hepatocytes from fibroblasts-the truth and myth of transdifferentiation

Hepatocyte transplantation is an alternative to liver transplantation in certain disorders such as inheritedliver diseases and liver failure.It is a relatively less complicated surgical procedure,and has the advantage that it can be repeated several times if unsuccessful.Another advantage is that hepatocytes can be isolated from partly damaged livers which are not suitable for liver transplantation.Despite these advantages hepatocyte transplantation is less popular.Important issues are poor engraftment of the transplanted cells and the scarcity of donor hepatocytes.Generation of "hepatocyte like cells"/i Heps from embryonic stem cells(ES) and induced pluripotent stem cells(iP SCs) by directed differentiation is an emerging solution to the latter issue.Direct conversation or trans-differentiation of fibroblasts to "hepatocyte like cells" is another way which is,being explored.However this method has several inherent and technical disadvantages compared to the directed differentiation from ES or i PSC.There are several methods claiming to be "highly efficient" for generating "highly functional" "hepatocyte like cells".Currently different groups are working independently and coming up with differentiation protocols and each group claiming an advantage for their protocol.Directed differentiation protocols need to be designed,compared,analyzed and tweaked systematically and logically than empirically.There is a need for a wellcoordinated global initiative comparable to the Human Genome Project to achieve this goal in the near future.