Embryonic Stem Cells Help Deliver 'Good Genes' in a Model of Inherited Blood Disorder

Embryonic Stem Cells Help Deliver 'Good Genes' in a Model of Inherited Blood Disorder
Thursday, 20 January 2011

Researchers at Nationwide Children's Hospital report a gene therapy strategy that improves the condition of a mouse model of an inherited blood disorder, Beta Thalassaemia. The gene correction involves using unfertilized eggs from afflicted mice to produce a batch of embryonic stem cell lines. Some of these stem cell lines do not inherit the disease gene and can thus be used for transplantation-based treatments of the same mice. Findings could hold promise for a new treatment strategy for autosomal dominant diseases like certain forms of Beta Thalassaemia, tuberous sclerosis or Huntington's disease.

Embryonic stem cells have the potential to produce unlimited quantities of any cell type and are therefore being explored as a new therapeutic option for many diseases. Unfertilized eggs can be cultured to form embryonic stem cells, so-called parthenogenetic embryonic stem cells.

"Parthenogenetic embryonic stem cells can differentiate into multiple tissue types as do stem cells from fertilized embryos," said K. John McLaughlin, PhD, principal investigator in the Center for Molecular and Human Genetics at The Research Institute at Nationwide Children's Hospital, Columbus, OH. Previously, the group demonstrated that blood cells derived from parthenogenetic cells could provide healthy, long-term blood replacement in mice.

"Advantages of parthenogenetic stem cells are not only that fertilization is not needed, but also that the recipient's immune system may potentially not view them as foreign, minimizing rejection problems. Furthermore, since parthenogenetic embryonic stem cells are derived from reproductive cells which contain only a single set of the genetic information instead of the double set present in body cells, they may not contain certain abnormal genes present in the other copy," said Dr. McLaughlin also one of the study authors.

A single copy of an abnormal gene inherited from one parent can cause so-called autosomal dominant diseases such as tuberous sclerosis or Huntington's disease. The affected person has one defective and one normal copy of the gene, but the abnormal gene overrides the normal gene, causing disease. In normal sexual reproduction, each parent provides one gene copy to offspring via their reproductive cells. Therefore, the reproductive cells of a patient with an autosomal dominant disease could either pass along a defective copy or a normal copy.

"As the donor patient has one defective gene copy and one normal, and only one copy is used for normal reproduction, we can select egg-cell-derived embryonic stem cells with two normal copies," said Dr. McLaughlin.

"These single-parent/patient-derived embryonic stem cells can theoretically be used for correction of a diverse number of diseases that occur when one copy of the gene is abnormal," said Dr. McLaughlin.

To test this theory, Dr. McLaughlin and colleagues from the University of Pennsylvania, University of North Carolina and University of Minnesota, examined whether parthenogenetic embryonic stem cells could be used for tissue repair in a mouse model of thalassaemia intermedia. Thalassaemia intermedia is an inherited blood disorder in which the body lacks sufficient normal haemoglobin, leading to excessive destruction of red blood cells and anaemia. They used a mouse model in which one defective gene copy causes anaemia.

Using approaches developed from a previous study done by this group, Nationwide Children's Research Fellow Sigrid Eckardt, PhD, derived embryonic stem cells from the unfertilized eggs of female mice with the disease, and identified those stem cell lines that contained only the "healthy" haemoglobin genes. These "genetically clean" embryonic stem cell lines were converted into cells that were transplanted into afflicted mice that were carriers of the disease-causing gene. Blood samples drawn five weeks after transplantation revealed that the delivered cells were present in the recipients' blood. Their red blood cells were also corrected to a size similar to normal mice and red blood cell count, hematocrit and haemoglobin levels became normal.

"Overall, we observed long-term improvement of thalassaemia in this model," said Dr. Eckardt.

"Our findings suggest that using reproductive cells to generate embryonic stem cells that are 'disease-free' may be a solution for genetic diseases involving large, complex or poorly identified deletions in the genome or that are not treatable by current gene therapy approaches."

Dr. McLaughlin says that this approach also contrasts with typical gene therapy approaches in that it requires no engineering of the genome, which is currently difficult to achieve in human embryonic and embryonic-like (IPS) stem cells.

Source: Nationwide Children's Hospital
Contact: Erin Pope
.........


ZenMaster

---

For more on stem cells and cloning, go to CellNEWS at
http://cellnews-blog.blogspot.com/

---

Stem Cell Research in China

From molecular physiology to therapeutic applications Wednesday, 29 July 2009 Stem cell research promises remedies to many devastating diseases that are currently incurable, ranging from diabetes and Parkinson's disease to paralysis. Totipotent embryonic stem cells have great potential for generating a wide range of different human cells that can be used to restore malfunctioning or damaged cells and tissues in patients. Recent studies have shown that pluripotent stem cells derived from adult bone marrow, the umbilical cord and the placenta could also be induced to differentiate into a variety of different tissues. In this issue, we have invited several scientists in China to summarize their pioneering works in the stem cell research field in the current issue of Science in China Series C - Life Sciences. Since 2001, Dr. Alex Yu Zhang has been a professor at Capital Medical University in Beijing and is Director of Cell Therapy Center at Xuanwu Hospital. His current research interest focuses on the understanding of basic biological properties of stem cells and developing nonhuman primate models for stem cell-based therapy of degenerative diseases. He has developed a stem cell mediated expression system for treating Parkinson's disease and his research using pancreatic progenitor cells for treating diabetes has demonstrated efficacy in monkey models. Professor Zhang has written an overview of cell replacement therapy of Parkinson's disease, which has been studied in both animal models and human patients for more than 20 years. Recent progress in stem cell biology has indicated that it is possible to avoid immunorejection of either nuclear transfer embryonic stem cells or induced pluripotent stem cells. On the other hand, recent post mortem analysis of patients who received foetal brain cell transplantation revealed that implanted cells are prone to degeneration just like endogenous neurons. Thus it appears that future cell replacement studies will have to focus on ameliorating disease symptoms as well as on slowing the progression of the disease [1]. Professor Robert Chunhua Zhao from the Chinese Academy of Medical Sciences is Executive Director of the National Center for Stem Cell Research. His group has taken stem cell therapy into phase II clinical trials in China, and is the leading runner in stem cell therapeutics. They have identified a mesenchymal stem cell (MSC) population from human foetal bone marrow and found that these cells could differentiate not only into osteogenic, adipogenic and endothelial lineages, but also hepatocyte-like cells, and neural and erythroid cells. They remained in some tissues and organs during gestation, could give rise to different kinds of pluripotent stem cells, and thus could potentially contribute to self-repair and self-renewal of tissues and organs. They generated cells not only for the damaged tissues in which they reside, but also for damaged tissues at other locations in the body via migration triggered by pro-inflammatory cytokines and growth factors. The potential use of MSCs in tissue regeneration has been shown in several models, including skin, muscle, lung, heart and the small intestine. MSCs have emerged as a promising therapeutic modality for tissue regeneration and autoimmune disease, although the mechanisms underlying the immune-modulatory effects of MSCs have not yet been clearly defined. In this review, Professor Robert Zhao summarizes the current literature on the complex mechanism of MSCs' immune modulation and clinical studies, and discusses future directions for utilizing MSCs for clinical treatments [2]. Professor Hongkui Deng from Peking University is working on the differentiation of human embryonic stem cells into pancreatic beta cells to treat diabetes. He is one of the two winners in China of the Bill and Melinda Gates Foundation's "Grand Challenges in Global Health". He obtained $1.9 million for his proposal to use stem cells to create mouse models for testing HIV and hepatitis C vaccines. Professor Deng has written a summary of recent progress in human embryonic and inducible pluripotent stem cell differentiation into functional pancreatic islet cells and discusses the challenges for future work [3]. Professor Qi Zhou is assistant Director of the Institute of Zoology at the Chinese Academy of Sciences. He has been studying the mechanism of differentiation and de-differentiation, cellular plasticity and totipotency of pluripotent cells, as well as that of somatic cells. He intends to build various cellular and animal models for human diseases, to uncover mechanisms underlying these different cellular processes and to discover new ways to improve cloning efficiency, which will provide a powerful tool for the study of mammalian reprogramming and ultimately offer important opportunities for regenerative medicine. Professor Zhou has helped to build the National Stem Cell Bank in Beijing, where clinical grade stem cell lines and patient specific cell lines have been created for future drug target candidate screening and therapeutic applications. Professor Qi Zhou has written a summary on human parthenogenetic embryonic stem cells as one potential resource for stem cell therapy[4]. Professor Lin Liu from Nankai University has been working on creating versatile patient-specific pluripotent stem cell lines that can be reliably used to fulfil the promise of stem cell therapy in regenerative medicine. Dr. Lin Liu's group found that pES cells generated from immature oocytes in mice exhibit pluripotency resembling fES cells, as evidenced by similarly high chimera production and germline transmission. Thus, immature eggs may provide an efficient source of autologous stem cells for regenerative medicine. This group also tested whether pESCs can be generated from older females. Dr. Lingyi Chen works on mechanisms of early embryonic differentiation. In their review of current special topics on stem cells, Drs. Lingyi Chen and Lin Liu analyze the current state of iPS research, particularly on limitations and advancements in this field, and propose possible future directions to meet the challenges of iPS cells for clinical applications [5]. Stem cell research has made significant progress in the past decade. Some therapeutic applications are coming closer to being on the market, but it is still hard to predict if and when stem cell therapy will replace largely traditional therapeutics. Given the early indications for success, we hope to see promising remedies for the many current incurable diseases being made available in the clinic over the coming years. References: 1 Ren Z, Zhang Y. Cell therapy for Parkinson's disease - So close and so far away. Sci China C-Life Sci, 2009, 52: 610—614 2 Wang L, Zhao R C. Mesenchymal stem cells targeting the GVHD. Sci China C-Life Sci, 2009, 52: 603—609 3 Zhang D, Jiang W, Shi Y, et al. Generation of Pancreatic islet cell from human embryonic stem cell. Sci China C-Life Sci, 2009, 52: 615—621 4 Hao J, Zhu W, Sheng C, et al. Human parthenogenetic embryonic stem cells: One potential resource for cell therapy. Sci China C-Life Sci, 2009, 52: 622—636 5 Chen L, Liu L. Current progress and prospect of induced pluripotent stem cell. Sci China C-Life Sci, 2009, 52: 622—636 ......... ZenMaster

---

For more on stem cells and cloning, go to CellNEWS at http://cellnews-blog.blogspot.com/ and http://www.geocities.com/giantfideli/index.html

---

California Company Creates Parthenogenetic hESC Lines

California Company Creates Parthenogenetic hESC Lines Thursday, 20 December 2007 Scientists at California-based International Stem Cell Corporation (ISCO) have created unique human stem cell lines that make them easily “immune matched” to human beings and could enable the creation of a bank of stem cells that could be used, without rejection, by a majority of the different people and races of the world. Akin to the concept of finding multiple “universal Type O blood donors”, the discovery is significant because it would eliminate the need for harsh immune suppression drugs currently used for cell transplant therapy. This may open the door to cell transplant therapy for diseases such as juvenile diabetes where the use of immune suppressant drugs is harmful to the patient. The findings are outlined in a scientific peer review paper entitled “HLA Homozygous Stem Cell Lines Derived from Human Parthenogenetic Blastocysts” which was announced in the December 19, 2007 online edition of Cloning and Stem Cells Journal. Of four unique human stem cell lines created, one line identified as hpSC-Hhom-4 was found to be a match with common immune types found in various races across the United States, opening the door to wide application in human therapeutics. The paper reports that for the Hhom-4 line, for example, therapeutic applications could be beneficial for tens of millions of people in the United States alone. “We are excited about this finding as it moves us closer to being able to cross-match stem cells for human transplant and build a true stem cell bank that could offer on-demand delivery of stem cells matched to a patient’s own immune system and eliminate the need for immunosuppressant drugs,” said Jeff Krstich, CEO of International Stem Cell Corporation. “Our intent is to begin clinical safety studies in animals immediately and utilize these hpSC-Hhom (or Hhom) cell lines to advance the field of regenerative medicine, as well as to commercialize our cells for cell transplant therapies.” One of the greatest risks with all transplants is immune rejection, notes Jeffrey Janus, Director of Scientific Research and co-author of the paper. “Immune suppressant drugs are usually required that result in a precarious balance that involves intentional compromise of the patient’s immune system to keep the body from rejecting the transplant, while still maintaining an immune system strong enough to defend against opportunistic infections and disease.” It is far more complicated in children, he added. “Children are more sensitive to the harsh effects of immune-suppressant drugs, thereby reducing therapeutic options and positive outcomes.” Transplant-based stem cell therapies face the same immune matching challenges as those faced by patients undergoing tissue and organ transplants. This makes ISCO’s creation of the Hhom stem cell lines a significant step toward achieving successful donor stem cell transplants. These new stem cell lines were created by ISCO lead scientist Dr. Elena Revazova using a process called “parthenogenesis”, which utilizes unfertilized human eggs and doesn’t destroy fertilized human embryos. International Stem Cell Corporation on June 27, 2007 announced that Dr. Revazova, one of the world’s leading cell biologists, had led a team in the first deliberate creation of human parthenogenetic stem lines. That breakthrough was outlined in a peer review paper entitled “Patient-Specific Stem Cell Lines Derived from Human Parthenogenetic Blastocysts”, and published in Cloning and Stem Cells Journal. That process then led to the current creation of the Hhom cell lines, which represent a “next major step” advancement of ISCO’s original parthenogenetic breakthrough. Data presented shows that the four new stem cell lines function similarly to those derived from fertilized human embryos and have the capacity to differentiate into the three germ layers of the body, meaning they have the ability to become any human cell type. Future work is focused on differentiating the Hhom cell lines into therapeutically useful cells. Although these Hhom lines are virtually animal contaminant free — a distinction likely to be critical for meeting Federal Drug Administration (FDA) approval for human clinical trials — the biggest advantage is that these parthenogenetically-derived stem cells have a simplified genetic code in the critical “HLA region” of the DNA, the region that gives a cell its immune profile to the outside world. The overall result produces a cell that is more easily matched with the immune systems of a far greater percentage of a population group. The paper reports that “with proper selection of oocyte donors according to HLA haplotype, and FDA approved manufacturing protocols, it is possible to generate a bank of cell lines whose tissue derivatives collectively could be MHC-matched with a significant number of individuals.” In explaining how the cell lines may be applied in populations worldwide, the paper notes: “It has been suggested that a panel of only ten HLA homozygous human stem cell lines selected for common types can provide a complete HLA-A, HLA-B and HLA-DR match for 37.7% of United Kingdom recipients, and a beneficial match for 67.4%.” In addressing the US population, the paper notes, “…calculations suggest that there are close to 200 common haplotypes per racial group. The hpSC-Hhom-4 line carries one of the most common haplotypes.” “We believe that Hhom lines are ideally suited for establishing a repository — a stem cell bank — of differentiated cells and tissues HLA-matched to population groups, which could be available for immediate clinical application,” added Krstich. “ISCO’s discovery significantly reduces the number of necessary stem cell lines needed to treat vast numbers of people. Moreover, the process is relatively efficient and reproducible.” The paper reports that aside from regenerative therapy, “a repository of cells and tissues derived from Hhom lines may be invaluable in the treatment of genetic disorders, “…including Alzheimer’s disease, diabetes, Graves disease, haemophilia, Huntington’s Disease, muscular dystrophy, Parkinson’s disease, sickle cell anaemia, Phenylketonuria-PKU and Severe Combined Immune Deficiency (SCID). Scientists must first change or “differentiate” the Hhom stem cells into the proper cell type to cure these diseases, but the Hhom lines should provide the best starting point for these studies. ......... See also: Chinese Groups Make Parthenogenetic hESCs Comments: More new lines of human parthenogenetic embryonic stem cells Cell Research (2008) 18:215–217. doi: 10.1038/cr.2008.19; published online 4 February 2008 ......... ZenMaster

---

For more on stem cells and cloning, go to CellNEWS at http://www.geocities.com/giantfideli/index.html

---

Chinese Groups Make Parthenogenetic hESCs

Two Chinese Groups Make Parthenogenetic hESCs Thursday, 13 December 2007 Two Chinese groups report this week, in the journal Cell Research, that they have obtained homozygous human ESC lines from a parthenogenetic oocyte, a process by which an oocyte is activated to develop without fusing with a sperm. Homozygous human embryonic stem cells (hESCs) are thought to be better cell sources for hESC banking because their histocompatibility would make it much more easy of finding matches for certain populations with relatively smaller groups of cell lines. Therefore they will be an important source of histocompatible cells and tissues for cell therapy in the future. The first group is lead by Guangxiu Lu at Central South University in Changsha, China. She has for a long period of time already worked with embryonic stem cells, and even claimed to have produced cloned human embryos several years ago. The other group is Shu-zhen Huang’s at the Institute of Medical Genetics, Shanghai Jiao Tong University School of Medicine, together with Qi Zhou’s laboratory in Beijing at the State Key Laboratory of Reproductive Biology, Institute of Zoology, the Chinese Academy of Sciences. Shu-zhen Huang is known for having created human-rabbit mixed embryos some years ago. Guangxiu Lu’s groups describe one cell line, while the other group succeeded to make two different cell lines. Both groups has carefully and detailed characterized their cells and determined they are of parthenogenetic origin by several techniques. References: A highly homozygous and parthenogenetic human embryonic stem cell line derived from a one-pronuclear oocyte following in vitro fertilization procedure Ge Lin, Qi OuYang, Xiaoying Zhou, Yifan Gu, Ding Yuan, Wen Li, Gang Liu, Tiancheng Liu & Guangxiu Lu Cell Res 2007 17: 999-1007; 10.1038/cr.2007.97 Derivation of human embryonic stem cell lines from parthenogenetic blastocysts Qingyun Mai, Yang Yu, Tao Li, Liu Wang, Mei-jue Chen, Shu-zhen Huang, Canquan Zhou & Qi Zhou Cell Res 2007 17: 1008-1019; 10.1038/cr.2007.102 Comments: More new lines of human parthenogenetic embryonic stem cells Cell Research (2008) 18:215–217. doi: 10.1038/cr.2008.19; published online 4 February 2008 ......... ZenMaster

---

For more on stem cells and cloning, go to CellNEWS at http://www.geocities.com/giantfideli/index.html

---

Was Hwang’s Stem Cells Parthenogenetic?

Was Hwang’s Stem Cells Parthenogenetic? Friday, 03 August 2007 Researchers say they have confirmed suspicions that embryonic stem cells claimed to be extracted from the first cloned human embryo by discredited South Korean scientist Woo Suk Hwang actually owe their existence to parthenogenesis, a process in which egg cells give rise to embryos without being fertilized by sperm. Read the whole article here: Was Hwang’s Stem Cells Parthenogenetic? ZenMaster