Stem cell medicine: umbilical cord blood and its stem cell potential

Ex vivo expansion of hematopoietic stem cells

Hematopoietic stem cells (HSCs) are multipotent progenitor cells that can differentiate into various mature blood cells and immune cells, thus reconstituting hematopoiesis. By taking advantage of the tremendous potential of HSCs, varied hereditary and hematologic diseases are promised to be alleviated or cured. To solve the contradiction between the growing demand for HSCs in disease treatment and the low population of HSCs in both cord blood and bone marrow, ex vivo HSC expansion along with multiple protocols has been investigated for harvesting adequate HSCs over the past two decades. This review surveys the state-of-the-art techniques for ex vivo HSC self-renewal and provides a concise summary of the effects of diverse intrinsic and extrinsic factors on the expansion of HSCs. The remaining challenges and emerging opportunities in the field of HSC expansion are also presented.

Clinical Practice of Umbilical Cord Blood Stem Cells in Transplantation and Regenerative Medicine - Prodigious Promise for Imminent Times

The umbilical cord blood is usually disposed of as an unwanted material after parturition; however, today, it is viewed as a regenerative medication so as to create the organ tissues. This cord blood gathered from the umbilical cord is made up of mesenchymal stem cells, hematopoietic stem cells, and multipotent non-hematopoietic stem cells having many therapeutic effects as these stem cells are utilized to treat malignancies, hematological ailments, inborn metabolic problem, and immune deficiencies. Presently, numerous clinical applications for human umbilical cord blood inferred stem cells, as stem cell treatment initiate new research. These cells are showing such a boon to stem cell treatment; it is nevertheless characteristic that the prospect of conservation of umbilical cord blood is gaining impetus. Current research works have demonstrated that about 80 diseases, including cancer, can be treated or relieved utilizing umbilical cord blood stem cells, and every year, many transplants have been effectively done around the world. However, in terms of factors, including patient selection, cell preparation, dosing, and delivery process, the treatment procedure for therapy with minimally manipulated stem cells can be patented. It is also worth thinking about how this patent could affect cord blood banks. Meanwhile, the utilization of cord blood cells is controversial and adult-derived cells may not be as successful, so numerous clinicians have begun working with stem cells that are acquired from umbilical cord blood. This review epitomizes a change in outlook from what has been completed with umbilical cord blood cell research and cord blood banking on the grounds that cord blood cells do not require much in the method of handling for cryopreservation or for transplantation in regenerative medicine.

Novel Cell-Based and Tissue Engineering Approaches for Induction of Angiogenesis as an Alternative Therapy for Diabetic Retinopathy

Diabetic retinopathy (DR) is the most frequent microvascular complication of long-term diabetes and the most common cause of blindness, increasing morbidity in the working-age population. The most effective therapies for these complications include laser photocoagulation and anti-vascular endothelial growth factor (VEGF) intravitreal injections. However, laser and anti-VEGF drugs are untenable as a final solution as they fail to address the underlying neurovascular degeneration and ischemia. Regenerative medicine may be a more promising approach, aimed at the repair of blood vessels and reversal of retinal ischemia. Stem cell therapy has introduced a novel way to reverse the underlying ischemia present in microvascular complications in diseases such as diabetes. The present review discusses current treatments, their side effects, and novel cell-based and tissue engineering approaches as a potential alternative therapeutic approach.

Current Status of Canine Umbilical Cord Blood-Derived Mesenchymal Stem Cells in Veterinary Medicine

Stem cell therapy has prompted the expansion of veterinary medicine both experimentally and clinically, with the potential to contribute to contemporary treatment strategies for various diseases and conditions for which limited or no therapeutic options are presently available. Although the application of various types of stem cells, such as bone marrow-derived mesenchymal stem cells (BM-MSCs), adipose tissue-derived mesenchymal stem cells (AT-MSCs), and umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs), has promising potential to improve the health of different species, it is crucial that the benefits and drawbacks are completely evaluated before use. Umbilical cord blood (UCB) is a rich source of stem cells; nonetheless, isolation of mesenchymal stem cells (MSCs) from UCB presents technical challenges. Although MSCs have been isolated from UCB of diverse species such as human, equine, sheep, goat, and canine, there are inherent limitations of using UCB from these species for the expansion of MSCs. In this review, we investigated canine UCB (cUCB) and compared it with UCB from other species by reviewing recent articles published from February 2003 to June 2017 to gain an understanding of the limitations of cUCB in the acquisition of MSCs and to determine other suitable sources for the isolation of MSCs from canine. Our review indicates that cUCB is not an ideal source of MSCs because of insufficient volume and ethical issues. However, canine reproductive organs discarded during neutering may help broaden our understanding of effective isolation of MSCs. We recommend exploring canine reproductive and adipose tissue rather than UCB to fulfill the current need in veterinary medicine for the well-designed and ethically approved source of MSCs.

Neural Stem Cells, Neural Progenitors, and Neurotrophic Factors

Neural stem cells (NSCs) have been proposed as a promising cellular source for the treatment of diseases in nervous systems. NSCs can self-renew and generate major cell types of the mammalian central nervous system throughout adulthood. NSCs exist not only in the embryo, but also in the adult brain neurogenic region: the subventricular zone (SVZ) of the lateral ventricle. Embryonic stem (ES) cells acquire NSC identity with a default mechanism. Under the regulations of leukemia inhibitory factor (LIF) and fibroblast growth factors, the NSCs then become neural progenitors. Neurotrophic and differentiation factors that regulate gene expression for controlling neural cell fate and function determine the differentiation of neural progenitors in the developing mammalian brain. For clinical application of NSCs in neurodegenerative disorders and damaged neurons, there are several critical problems that remain to be resolved: 1) how to obtain enough NSCs from reliable sources for autologous transplantation; 2) how to regulate neural plasticity of different adult stem cells; 3) how to control differentiation of NSCs in the adult nervous system. In order to understand the mechanisms that control NSC differentiation and behavior, we review the ontogeny of NSCs and other stem cell plasticity of neuronal differentiation. The role of NSCs and their regulation by neurotrophic factors in CNS development are also reviewed.

Different Tissue-Derived Stem Cells: A Comparison of Neural Differentiation Capability

BACKGROUND

Stem cells are capable of self-renewal and differentiation into a wide range of cell types with multiple clinical and therapeutic applications. Stem cells are providing hope for many diseases that currently lack effective therapeutic methods, including strokes, Huntington's disease, Alzheimer's and Parkinson's disease. However, the paucity of suitable cell types for cell replacement therapy in patients suffering from neurological disorders has hampered the development of this promising therapeutic approach.

AIM

The innovative aspect of this study has been to evaluate the neural differentiation capability of different tissue-derived stem cells coming from different tissue sources such as bone marrow, umbilical cord blood, human endometrium and amniotic fluid, cultured under the same supplemented media neuro-transcription factor conditions, testing the expression of neural markers such as GFAP, Nestin and Neurofilaments using the immunofluorescence staining assay and some typical clusters of differentiation such as CD34, CD90, CD105 and CD133 by using the cytofluorimetric test assay.

RESULTS

Amniotic fluid derived stem cells showed a more primitive phenotype compared to the differentiating potential demonstrated by the other stem cell sources, representing a realistic possibility in the field of regenerative cell therapy suitable for neurodegenerative diseases.

An Overview on Human Umbilical Cord Blood Stem Cell-Based Alternative In Vitro Models for Developmental Neurotoxicity Assessment

The developing brain is found highly vulnerable towards the exposure of different environmental chemicals/drugs, even at concentrations, those are generally considered safe in mature brain. The brain development is a very complex phenomenon which involves several processes running in parallel such as cell proliferation, migration, differentiation, maturation and synaptogenesis. If any step of these cellular processes hampered due to exposure of any xenobiotic/drug, there is almost no chance of recovery which could finally result in a life-long disability. Therefore, the developmental neurotoxicity (DNT) assessment of newly discovered drugs/molecules is a very serious concern among the neurologists. Animal-based DNT models have their own limitations such as ethical concerns and lower sensitivity with less predictive values in humans. Furthermore, non-availability of human foetal brain tissues/cells makes job more difficult to understand about mechanisms involve in DNT in human beings. Although, the use of cell culture have been proven as a powerful tool for DNT assessment, but many in vitro models are currently utilizing genetically unstable cell lines. The interpretation of data generated using such terminally differentiated cells is hard to extrapolate with in vivo situations. However, human umbilical cord blood stem cells (hUCBSCs) have been proposed as an excellent tool for alternative DNT testing because neuronal development from undifferentiated state could exactly mimic the original pattern of neuronal development in foetus when hUCBSCs differentiated into neuronal cells. Additionally, less ethical concern, easy availability and high plasticity make them an attractive source for establishing in vitro model of DNT assessment. In this review, we are focusing towards recent advancements on hUCBSCs-based in vitro model to understand DNTs.

Impact of umbilical cord blood-derived mesenchymal stem cells on cardiovascular research

Over the years, cell therapy has become an exciting opportunity to treat human diseases. Early enthusiasm using adult stem cell sources has been tempered in light of preliminary benefits in patients. Considerable efforts have been dedicated, therefore, to explore alternative cells such as those extracted from umbilical cord blood (UCB). In line, UCB banking has become a popular possibility to preserve potentially life-saving cells that are usually discarded after birth, and the number of UCB banks has grown worldwide. Thus, a brief overview on the categories of UCB banks as well as the properties, challenges, and impact of UCB-derived mesenchymal stem cells (MSCs) on the area of cardiovascular research is presented. Taken together, the experience recounted here shows that UCBMSCs are envisioned as attractive therapeutic candidates against human disorders arising and/or progressing with vascular deficit.

Non-hematopoietic stem cells in umbilical cord blood

Allogeneic umbilical cord blood (UCB) transplantation has been used to treat a variety of malignant and non-malignant diseases. Recent studies show convincing evidence that UCB contains not only hematopoietic progenitors, but also several types of stem and progenitor cells providing a high proliferative capacity and a variety of differentiation potentials. UCB-derived cells offer multiple advantages over adult stem cells from other sources like bone marrow (BM), because UCB can be collected without painful procedure, easily available in virtually unlimited supply, and has not been exposed to immunologic challenge. In addition, cord blood transplantation is now an established field with great potential and no serious ethical issue by establishment of public UCB banks throughout the world. Therefore UCB-derived non-hematopoietic stem cells may provide an attractive cell source for tissue repair and regeneration. It is generally accepted that UCB contains endothelial progenitor cells (EPC), mesenchymal stromal cells (MSC), unrestricted somatic stem cells (USSC), very small embryonic-like stem cells (VSEL), multilineage progenitor cells (MLPC), and neuronal progenitor cells. This review focuses on biological properties of these non-hematopoietic stem/progenitor cells derived from human UCB and their potential use in cell based therapies.

Transplantation of umbilical cord blood-derived cells for novel indications in regenerative therapy or immune modulation: a scoping review of clinical studies

Although used mainly for transplantation of hematopoietic stem cells in the treatment of blood disorders, umbilical cord blood (UCB)-based therapies are now being used increasingly for novel applications in nonhematopoietic diseases and as a form of cellular regenerative therapy or immune modulation. We performed a systematic scoping review by searching Medline, EMBASE, and the Cochrane Library for published articles, and we searched www.clinicaltrials.com and the World Health Organization International Clinical Trials Registry Platform to describe the breadth of published studies and ongoing clinical activity in umbilical cord-based cellular therapy for regenerative therapy and immune modulation. The most commonly published area of expertise in the use of UCB-derived cellular transplantation for novel indications is for neurological disorders and this remains the most active area of study in ongoing registered trials. An increasingly broad range of disorders, however, are reflected in ongoing registered trials, which suggests greater activity, interest, and investment in UCB-derived cellular therapy. Interestingly, adult patients compose the majority of patients reported in published reports and registered ongoing clinical studies continue to enroll predominantly adult subjects. Geographically, Asian countries appear most active in UCB-derived cellular therapy and our analysis of ongoing studies suggests this trend will likely continue. Regular assessment of published and ongoing activity in UCB transplantation for emerging novel indications will be critical for informing UCB banking establishments and funding agencies to guide changes in banking practices related to emerging trends in cell therapy.

Baculovirus as an ideal radionuclide reporter gene vector: a new strategy for monitoring the fate of human stem cells in vivo

PURPOSE

Radionuclide reporter gene imaging holds promise for non-invasive monitoring of transplanted stem cells. Thus, the feasibility of utilizing recombinant baculoviruses carrying the sodium iodide symporter (NIS) reporter gene in monitoring stem cell therapy by radionuclide imaging was explored in this study.

METHODS

Recombinant baculoviruses carrying NIS and green fluorescent protein (GFP) reporter genes (Bac-NIS and Bac-GFP) were constructed and used to infect human induced pluripotent stem cells (hiPSCs), human embryonic stem cells (hESCs) and human umbilical cord blood mesenchymal stem cells (hUCB-MSCs). Infection efficiency, total fluorescence intensity and duration of transgene expression were determined by flow cytometry. Cytotoxicity/proliferative effects of baculovirus on hUCB-MSCs were assessed using CCK-8 assays. ¹²⁵I uptake and perchlorate inhibition assays were performed on Bac-NIS-infected hUCB-MSCs. Radionuclide imaging of mice transplanted with Bac-NIS-infected hUCB-MSCs was performed by NanoSPECT/CT imaging.

RESULTS

Infection efficiencies of recombinant baculovirus in hESCs, hiPSCs and hUCB-MSCs increased with increasing MOIs (27.3%, 35.8% and 95.6%, respectively, at MOI = 800). Almost no cytotoxicity and only slight effects on hUCB-MSCs proliferation were observed. Obvious GFP expression (40.6%) remained at 8 days post-infection. The radioiodide was functionally accumulated by NIS gene products and specifically inhibited by perchlorate (ClO₄⁻). Radioiodide uptake, peaking at 30 min and gradually decreasing over time, significantly correlated with hUCB-MSCs cell number (R² = 0.994). Finally, radionuclide imaging showed Bac-NIS-infected hUCB-MSCs effectively accumulated radioiodide in vivo, which gradually weakened over time.

CONCLUSION

Baculovirus as transgenic vector of radionuclide reporter gene imaging technology is a promising strategy for monitoring stem cell transplantation therapy.

Potential role of stem cells in severe spinal cord injury: current perspectives and clinical data

Stem cell transplantation for spinal cord injury (SCI) along with new pharmacotherapy research offers the potential to restore function and ease the associated social and economic burden in the years ahead. Various sources of stem cells have been used in the treatment of SCI, but the most convincing results have been obtained with neural progenitor cells in preclinical models. Although the use of cell-based transplantation strategies for the repair of chronic SCI remains the long sought after holy grail, these approaches have been to date the most successful when applied in the subacute phase of injury. Application of cell-based strategies for the repair and regeneration of the chronically injured spinal cord will require a combinational strategy that may need to include approaches to overcome the effects of the glial scar, inhibitory molecules, and use of tissue engineering strategies to bridge the lesion. Nonetheless, cell transplantation strategies are promising, and it is anticipated that the Phase I clinical trials of some form of neural stem cell-based approach in SCI will commence very soon.

Cord blood endothelial progenitor cells as therapeutic and imaging probes

Numerous studies demonstrated that neovascularization processes associated with severe tissue ischemia commonly found in conditions such as cardiovascular disorders and tumor growth occur via angiogenic and vasculogenic mechanisms. Over the past decade, it has been demonstrated that endothelial progenitor cells (EPCs) play a significant role in neo-angiogenic and neovasculogenic processes. Due to their ability to self-renew, circulate, home to the ischemic sites and differentiate into mature endothelial cells, EPCs derived from various sources hold enormous potential to be used as therapeutic agents in pro- or anti-angiogenic strategies for the treatment of ischemic and tumor conditions, respectively. However, the development of EPC-based therapies requires accompanying, noninvasive imaging protocol for in vivo tracking of transplanted cells. Hence, this review focuses on cord blood-derived EPCs and their role in neovascularization with emphasis on the potential use of EPCs as a therapeutic and imaging probe.

MRI tracking of FePro labeled fresh and cryopreserved long term in vitro expanded human cord blood AC133+ endothelial progenitor cells in rat glioma

BACKGROUND

Endothelial progenitors cells (EPCs) are important for the development of cell therapies for various diseases. However, the major obstacles in developing such therapies are low quantities of EPCs that can be generated from the patient and the lack of adequate non-invasive imaging approach for in vivo monitoring of transplanted cells. The objective of this project was to determine the ability of cord blood (CB) AC133+ EPCs to differentiate, in vitro and in vivo, toward mature endothelial cells (ECs) after long term in vitro expansion and cryopreservation and to use magnetic resonance imaging (MRI) to assess the in vivo migratory potential of ex vivo expanded and cryopreserved CB AC133+ EPCs in an orthotopic glioma rat model.

MATERIALS, METHODS AND RESULTS

The primary CB AC133+ EPC culture contained mainly EPCs and long term in vitro conditions facilitated the maintenance of these cells in a state of commitment toward endothelial lineage. At days 15-20 and 25-30 of the primary culture, the cells were labeled with FePro and cryopreserved for a few weeks. Cryopreserved cells were thawed and in vitro differentiated or i.v. administered to glioma bearing rats. Different groups of rats also received long-term cultured, magnetically labeled fresh EPCs and both groups of animals underwent MRI 7 days after i.v. administration of EPCs. Fluorescent microscopy showed that in vitro differentiation of EPCs was not affected by FePro labeling and cryopreservation. MRI analysis demonstrated that in vivo accumulation of previously cryopreserved transplanted cells resulted in significantly higher R2 and R2* values indicating a higher rate of migration and incorporation into tumor neovascularization of previously cryopreserved CB AC133+ EPCs to glioma sites, compared to non-cryopreserved cells.

CONCLUSION

Magnetically labeled CB EPCs can be in vitro expanded and cryopreserved for future use as MRI probes for monitoring the migration and incorporation to the sites of neovascularization.

Cell-based therapy for prevention and reversal of myocardial remodeling

Although pharmacological and interventional advances have reduced the morbidity and mortality of ischemic heart disease, there is an ongoing need for novel therapeutic strategies that prevent or reverse progressive ventricular remodeling following myocardial infarction, the process that forms the substrate for ventricular failure. The development of cell-based therapy as a strategy to repair or regenerate injured tissue offers extraordinary promise for a powerful anti-remodeling therapy. In this regard, the field of cell therapy has made major advancements in the past decade. Accumulating data from preclinical studies have provided novel insights into stem cell engraftment, differentiation, and interactions with host cellular elements, as well as the effectiveness of various methods of cell delivery and accuracy of diverse imaging modalities to assess therapeutic efficacy. These findings have in turn guided rationally designed translational clinical investigations. Collectively, there is a growing understanding of the parameters that underlie successful cell-based approaches for improving heart structure and function in ischemic and other cardiomyopathies.

Ensheathing cell-conditioned medium directs the differentiation of human umbilical cord blood cells into aldynoglial phenotype cells

Despite their similarities to bone marrow precursor cells (PC), human umbilical cord blood (HUCB) PCs are more immature and, thus, they exhibit greater plasticity. This plasticity is evident by their ability to proliferate and spontaneously differentiate into almost any cell type, depending on their environment. Moreover, HUCB-PCs yield an accessible cell population that can be grown in culture and differentiated into glial, neuronal and other cell phenotypes. HUCB-PCs offer many potential therapeutic benefits, particularly in the area of neural replacement. We sought to induce the differentiation of HUCB-PCs into glial cells, known as aldynoglia. These cells can promote neuronal regeneration after lesion and they can be transplanted into areas affected by several pathologies, which represents an important therapeutic strategy to treat central nervous system damage. To induce differentiation to the aldynoglia phenotype, HUCB-PCs were exposed to different culture media. Mononuclear cells from HUCB were isolated and purified by identification of CD34 and CD133 antigens, and after 12 days in culture, differentiation of CD34+ HUCB-PCs to an aldynoglia phenotypic, but not that of CD133+ cells, was induced in ensheathing cell (EC)-conditioned medium. Thus, we demonstrate that the differentiation of HUCB-PCs into aldynoglia cells in EC-conditioned medium can provide a new source of aldynoglial cells for use in transplants to treat injuries or neurodegenerative diseases.

Stem cells for spinal cord regeneration: Current status

Background:

Nearly 11,000 cases of spinal cord injury (SCI) are reported in the United States annually. Current management options give a median survival time of 38 years; however, no rehabilitative measures are available. Stem cells have been under constant research given their ability to differentiate into neural cell lines replacing non functional tissue. Efforts have been made to establish new synapses and provide a conducive environment, by grafting cells from autologous and fetal sources; including embryonic or adult stem cells, Schwann cells, genetically modified fibroblasts, bone stromal cells, and olfactory ensheathing cells and combinations/ variants thereof.

Methods:

In order to discuss the underlying mechanism of SCI along with the previously mentioned sources of stem cells in context to SCI, a simple review of literature was conducted. An extensive literature search was conducted using the PubMed data base and online search engines and articles published in the last 15 years were considered along with some historical articles where a background was required.

Results:

Stem cell transplantation for SCI is at the forefront with animal and in vitro studies providing a solid platform to enable well-designed human studies. Olfactory ensheathing cells seem to be the most promising; whilst bone marrow stromal cells appear as strong candidates for an adjunctive role.

Conclusion:

The key strategy in developing the therapeutic basis of stem cell transplantation for spinal cord regeneration is to weed out the pseudo-science and opportunism. All the trials should be based on stringent scientific criteria and effort to bypass that should be strongly discouraged at the international level.

Human umbilical cord blood cells form epidermis in the skin equivalent model

Recently, human embryonic stem cells have been differentiated in vitro into functional epidermal keratinocytes. Here, we demonstrated that these cells can be generated also from non-embryonic, human umbilical cord blood (hUCB) cells that have the potential to differentiate into cells of non-hematopoietic lineage. Human UCB mono-nucleated cells were cultivated in monolayer and in three-dimensional skin equivalent cultures and assayed for the presence of phenotype-specific markers. Our results determined that after one month of culturing in serum containing medium, the hUCB cells produced morphologically homogeneous colonies of epithelial cells expressing keratinocyte-specific markers. They also formed stratified epidermis in organ cultures that contained sporadic CD1a-positive cells within the accurate strata. We concluded that hUCB cells have the capacity to differentiate into functional epidermal keratinocytes and may serve as a source of high-quality keratinocytes for clinical applications.

Morphology of in vitro expanded human muscle-derived stem cells

BACKGROUND

Skeletal muscle contains populations of multipotent adult stem cells also referred to as muscle-derived stem cells.

AIM

The main goal of this study was to isolate and culture human adult stem cells from skeletal muscle and characterize them.

METHODS

Muscle-derived stem cells were isolated from biopsy specimens of femoral muscle. The cells were cultured in Dulbecco's modified Eagle's minimal essential medium supplemented with 10% fetal calf serum and gentamycin. When they reached confluence, they were sub-passaged up to the third passage. Cells from the last passage were prepared for TEM analysis. Production of alpha-actin and desmin was confirmed by histochemistry. Moreover, the phenotypic characterization was performed.

RESULTS

Primary isolated muscle-derived stem cells had a fibroblast-like shape. During subsequent passages they maintained this morphology. TEM analysis showed typical ultrastructural morphology of mesenchymal stem cells. They had large pale nuclei with a large amount of euchromatine. Nuclei were irregular with noticeable nucleoli. Dilated cisterns of rough endoplasmic reticulum were present in cytoplasm. In certain parts of the cytoplasm there were aggregates of granules of glycogen. The products of cells were actively secreted into the extracellular matrix. They expressed alpha-actin and desmin. The results of phenotypic characterization showed that almost all analyzed cells were CD13, CD34, CD56 positive and CD45 negative. Moreover, they did not express anti-human fibroblast surface protein.

CONCLUSIONS

Muscle-derived stem cells exhibited typical characteristics typical for mesenchymal stem cells. After analysis of their differentiation potential they could be used in tissue engineering and regenerative medicine.

Cryopreservation of hematopoietic stem/progenitor cells for therapeutic use

To date, more than 25,000 hematopoietic transplants have been carried out across Europe for hematological disorders, the majority being for hematological malignancies. At least 70% of these are autologous transplants, the remaining 30% being allogeneic, which are sourced from related (70% of the allogeneic) or unrelated donors. Peripheral blood mobilized with granulocyte colony stimulating factor is the major source of stem cells for transplantation, being used in approx 95% of autologous transplants and in approx 65% of allogeneic transplants. Other cell sources used for transplantation are bone marrow and umbilical cord blood. One crucial advance in the treatment of these disorders has been the development of the ability to cryopreserve hematopoietic stem cells for future transplantation. For bone marrow and mobilized peripheral blood, the majority of cryopreserved harvests come from autologous collections that are stored prior to a planned infusion following further treatment of the patient or at the time of a subsequent relapse. Other autologous harvests are stored as backup or "rainy day" harvests, the former specifically being intended to rescue patients who develop graft failure following an allogeneic transplant or who may require this transplant at a later date. Allogeneic bone marrow and mobilized peripheral blood are less often cryopreserved than autologous harvests. This is in contrast to umbilical cord blood that may be banked for directed or sibling (related) hematopoietic stem cell transplants, for allogeneic unrelated donations, and for autologous donations. Allogeneic unrelated donations are of particular use for providing a source of hematopoietic stem cells for ethnic minorities, patients with rare human leukocyte antigen types, or where the patient urgently requires a transplant and cannot wait for the weeks to months required to prepare a bone marrow donor. There are currently more than 200,000 banked umbilical cord blood units registered with the Bone Marrow Donors Worldwide registry. In this chapter, we describe several protocols that we have used to cryopreserve these different sources of hematopoietic stem/progenitor cells, keeping in mind that the protocols may vary among transplant processing centers.

Cell engineering and molecular pharming for biopharmaceuticals

Biopharmaceuticals are often produced by recombinant E. coli or mammalian cell lines. This is usually achieved by the introduction of a gene or cDNA coding for the protein of interest into a well-characterized strain of producer cells. Naturally, each recombinant production system has its own unique advantages and disadvantages. This paper examines the current practices, developments, and future trends in the production of biopharmaceuticals. Platform technologies for rapid screening and analyses of biosystems are reviewed. Strategies to improve productivity via metabolic and integrated engineering are also highlighted.

The role of blood services and regulatory bodies in stem cell transplantation

Advances in stem cell research over the past few decades have coincided with large increases in haemopoietic stem cell transplantation (HSCT) using either bone marrow, peripheral blood or cord blood-derived stem cells. Alongside this growth has come an increase in the role played by regulatory bodies, both governmental and professional, to ensure that those undertaking such procedures do so in a manner so as to minimize the risk to patients. Interestingly, government legislation encompasses not only cellular therapies, but also the use of tissues and organs, as many of the processes and procurement procedures involved are similar. In this review, we analyse the trends in HSCT, describe the development and impact of legislation within Europe on this practice and outline the vital role played by the UK blood services in providing robust and high-quality HSCT services.

Potential for access to embryonic-like cells from human umbilical cord blood

All too often media attention clouds the reality that there are many types of stem cell. The embryos, bone marrow and umbilical cord blood (UCB) are the three most used sources. However, despite what it would appear, embryonic stem cells have not been the first to yield life-saving cures at present. Faster routes to clinical intervention have been using adult stem cells that can be sourced from bone marrow and from cord blood, and that are readily accessible and are more ethically acceptable to the general public. Both these non-embryonic sources have been able to provide sufficient numbers of cells to allow development of clinical translational protocols. Bone marrow-derived cells have been used successfully in myocardial infarct therapy where relining by endothelial tissue has allowed limited reperfusion to damaged cardiac tissue. UCB have also demonstrated significant success for around 20 years in haematotransplantation. With a global human population in excess of 6 billion, births thus UCB, remain the largest untouched source of stem cells available every year. UCB also provide a distinct advantage over other adult stem cells due to the length of the telomere and also due protected immunological status of the developing neonatal environment. The total mutation load in the UCB populations is clearly likely to be significant less than in adult tissues.

Authoritative regulation and the stem cell debate

In this paper I argue that liberal democratic communities are justified in regulating the activities of their members because of the inevitable existence of conflicting conceptions of what is considered as morally right. This will often lead to tension and disputes, and in such circumstances, reliance on peaceful or orderly co-existence will not normally suffice. In such pluralistic societies, the boundary between permissible and impermissible activities will be unclear; and this becomes a particular concern in controversial issues which raise specific anxieties and uncertainty. One context that has repeatedly raised issues in this regard is that of biotechnology and, in particular, the recent stem cell debate, on which this paper concentrates. While such developments have the potential to make significant improvements to therapeutic progress, we should also be sceptical because predicting the impact of these developments remains uncertain and complex. For the sake of socio-political stability, it will therefore be necessary to enact and enforce rules which limit these competing claims in public policy but which may not be compatible with what individual moral commitments ideally permit. One way to achieve this is to establish procedural frameworks to resolve potential disputes in the public sphere about what is right, wrong, or permissible conduct. I argue that for one to commit to authoritative regulation, an idea of harm prevention through state intervention is necessary; and that this requires optimum mechanisms of procedure which allow the individual the opportunity to compromise and yet to continue to oppose or fight for changes as demanded by his or her moral position.

Transplantation of canine umbilical cord blood-derived mesenchymal stem cells in experimentally induced spinal cord injured dogs

This study was to determine the effects of allogenic umbilical cord blood (UCB)-derived mesenchymal stem cells (MSCs) and recombinant methionyl human granulocyte colony-stimulating factor (rmhGCSF) on a canine spinal cord injury model after balloon compression at the first lumbar vertebra. Twenty-five adult mongrel dogs were assigned to five groups according to treatment after a spinal cord injury: no treatment (CN); saline treatment (CP); rmhGCSF treatment (G); UCB-MSCs treatment (UCB-MSC); co-treatment (UCBG). The UCB-MSCs isolated from cord blood of canine fetuses were prepared as 10⁶ cells/150 µl saline. The UCB-MSCs were directly injected into the injured site of the spinal cord and rmhGCSF was administered subcutaneously 1 week after the induction of spinal cord injury. The Olby score, magnetic resonance imaging, somatosensory evoked potentials and histopathological examinations were used to evaluate the functional recovery after transplantation. The Olby scores of all groups were zero at the 0-week evaluation. At 2 week after the transplantation, the Olby scores in the groups with the UCB-MSC and UCBG were significantly higher than in the CN and CP groups. However, there were no significant differences between the UCB-MSC and UCBG groups, and between the CN and CP groups. These comparisons remained stable at 4 and 8 week after transplantation. There was significant improvement in the nerve conduction velocity based on the somatosensory evoked potentials. In addition, a distinct structural consistency of the nerve cell bodies was noted in the lesion of the spinal cord of the UCB-MSC and UCBG groups. These results suggest that transplantation of the UCB-MSCs resulted in recovery of nerve function in dogs with a spinal cord injury and may be considered as a therapeutic modality for spinal cord injury.

The potential of umbilical cord blood multipotent stem cells for nonhematopoietic tissue and cell regeneration

Stem cells have been isolated from human embryos, fetal tissue, umbilical cord blood (UCB), and also from "adult" sources. Adult stem cells are found in many tissues of the body and are capable of maintaining, generating, and replacing terminally differentiated cells. A source of pluripotent stem cells has been recently identified in UCB that can also differentiate across tissue lineage boundaries into neural, cardiac, epithelial, hepatocytic, and dermal tissue. Thus, UCB may provide a future source of stem cells for tissue repair and regeneration. Its widespread availability makes UCB an attractive source for tissue regeneration. UCB-derived stem cells offer multiple advantages over adult stem cells, including their immaturity, which may play a significant role in reduced rejection after transplantation into a mismatched host and their ability to produce larger quantities of homogenous tissue or cells. While research with embryonic stem cells continues to generate considerable controversy, human umbilical stem cells provide an alternative cell source that has been more ethically acceptable and appears to have widespread public support. This review will summarize the in vitro and in vivo studies examining UCB stem cells and their potential use for therapeutic application for nonhematopoietic tissue and cell regeneration.

Directed sibling cord blood banking for transplantation: the 10-year experience in the national blood service in England

Umbilical cord blood (UCB) is an important source of hematopoietic stem cells for transplantation. Although UCB is often collected from unrelated donors, directed umbilical cord blood (DCB) from sibling donors also provides an important source of UCB for transplantation. This report summarizes the experience in collection, testing, storage, and transplantation of DCB units by the National Blood Service for England and North Wales over 10 years. Eligibility for collection was based on an existing sibling suffering from a disease that may be treated by stem cell transplantation or a family history that could result in the birth of a sibling with a disease that could be treated by stem cell transplantation. Collections were made on the provision that the sibling's clinician was willing to financially support the collection and to take responsibility for medical review of the mother and potential recipient. Given the high investment in UCB banking and the introduction of new regulations and mandatory licensing under the European Union Tissues and Cells Directive and those proposed in the U.S., this report details the procedures that we have used for DCB donations, the outcome data where donations have been used for transplantation, and it provides some timely recommendations for best practices. Disclosure of potential conflicts of interest is found at the end of this article.

Isolation of mesenchymal stem cells from equine umbilical cord blood

Background

There are no published studies on stem cells from equine cord blood although commercial storage of equine cord blood for future autologous stem cell transplantations is available. Mesenchymal stem cells (MSC) have been isolated from fresh umbilical cord blood of humans collected non-invasively at the time of birth and from sheep cord blood collected invasively by a surgical intrauterine approach. Mesenchymal stem cells isolation percentage from frozen-thawed human cord blood is low and the future isolation percentage of MSCs from cryopreserved equine cord blood is therefore expectedly low. The hypothesis of this study was that equine MSCs could be isolated from fresh whole equine cord blood.

Results

Cord blood was collected from 7 foals immediately after foaling. The mononuclear cell fraction was isolated by Ficoll density centrifugation and cultured in a DMEM low glucose based media at 38.5°C in humidified atmosphere containing 5% CO₂. In 4 out of 7 samples colonies with MSC morphology were observed. Cellular morphology varied between monolayers of elongated spindle-shaped cells to layered cell clusters of cuboidal cells with shorter cytoplasmic extensions. Positive Alizarin Red and von Kossa staining as well as significant calcium deposition and alkaline phosphatase activity confirmed osteogenesis. Histology and positive Safranin O staining of matrix glycosaminoglycans illustrated chondrogenesis. Oil Red O staining of lipid droplets confirmed adipogenesis.

Conclusion

We here report, for the first time, the isolation of mesenchymal-like stem cells from fresh equine cord blood and their differentiation into osteocytes, chondrocytes and adipocytes. This novel isolation of equine cord blood MSCs and their preliminary in vitro differentiation positions the horse as the ideal pre-clinical animal model for proof-of-principle studies of cord blood derived MSCs.

Collection strategies and cryopreservation of umbilical cord blood

The aim of this study was to compare (a) two different umbilical cord blood (UCB) collection methods while the placenta is still in the uterus (in utero), and (b) to evaluate the efficacy of four cryopreservation protocols based on UCB haematopoiestic stem cell (HSC) recovery. We analysed UCB samples collected with our original collection system designed for active Syringe/Flush/Syringe method or by standard in utero method. For comparing different cryopreservation procedures, dimethyl sulphoxide (DMSO) at final concentration of 5 and 10% was used and combined with our own controlled-rate or uncontrolled-rate cryopreservation. A total of 99 samples were collected. A significantly higher UCB volume, total nucleated cell and mononuclear cell were seen following the first collection strategy (n= 49; mean +/- SD, 103 +/- 35.4 mL; 12.34 +/- 5.27 x 10(8); 595 +/- 3.47 x 10(6)) vs. the second strategy (n= 50; 86 +/- 29.3 mL; 9.87 +/- 4.47; 424 +/- 2.82 x 10(6)) respectively (P < 0.01). The discard rate was 14% for the first and 36% for the second collection strategy (P < 0.01). It was shown that the most efficient procedure was the controlled-rate protocol combined with lower (5%) DMSO concentration. Using active Syringe/Flush/Syringe method, we collected UCB with greater volumes and with lower discard rate compared to the standard by gravity technique. The data presented also showed much better recovery of UCB cells when controlled-rate freezing procedure and 5% DMSO were combined.

Transcriptional profiling of human cord blood CD133+ and cultured bone marrow mesenchymal stem cells in response to hypoxia

Umbilical cord blood (UCB) and bone marrow (BM)-derived stem and progenitor cells possess two characteristics required for successful tissue regeneration: extensive proliferative capacity and the ability to differentiate into multiple cell lineages. Within the normal BM and in pathological conditions, areas of hypoxia may have a role in maintaining stem cell fate or determining the fine equilibrium between their proliferation and differentiation. In this study, the transcriptional profiles and proliferation and differentiation potential of UCB CD133(+) cells and BM mesenchymal cells (BMMC) exposed to normoxia and hypoxia were analyzed and compared. Both progenitor cell populations responded to hypoxic stimuli by stabilizing the hypoxia inducible factor (HIF)-1alpha protein. Short exposures to hypoxia increased the clonogenic myeloid capacity of UCB CD133(+) cells and promoted a significant increase in BMMC number. The differentiation potential of UCB CD133(+) clonogenic myeloid cells was unaltered by short exposures to hypoxia. In contrast, the chondrogenic differentiation potential of BMMCs was enhanced by hypoxia, whereas adipogenesis and osteogenesis were unaltered. When their transcriptional profiles were compared, 183 genes in UCB CD133(+) cells and 45 genes in BMMC were differentially regulated by hypoxia. These genes included known hypoxia-responsive targets such as BNIP3, PGK1, ENO2, and VEGFA, and other genes not previously described to be regulated by hypoxia. Several of these genes, namely CDTSPL, CCL20, LSP1, NEDD9, TMEM45A, EDG-1, and EPHA3 were confirmed to be regulated by hypoxia using quantitative reverse transcriptase polymerase chain reaction. These results, therefore, provide a global view of the signaling and regulatory network that controls oxygen sensing in human adult stem/progenitor cells derived from hematopoietic tissues.

A small-scale serum-free liquid cell culture model of erythropoiesis to assess the effects of exogenous factors

Anaemia is an important global health problem. Therefore, it is crucial to understand its pathophysiology in various genetic or infectious diseases where dyserythropoiesis is a key pathological feature. To this effect, reproducible and reliable models of erythropoiesis in vitro are much needed as investigative tools. We have developed a serum-free liquid culture model of erythropoiesis using human umbilical cord blood CD34(+) cells cultured in the cytokine combination, interleukin-3 (IL-3), IL-6, stem cell factor (SCF) and erythropoietin (Epo), over 14 days. We found that these culture conditions favored erythroid differentiation over the expansion of the more primitive erythroid precursors. With an initiating culture density of 5x10(4) cells per ml, the nucleated cell fold expansion increased from 7.9+/-3.9 (range 4.5 to 11.1) after 4 days to 2990.2+/-1936.1 (range 626.6 to 6912.0) after 14 days in culture. Day-14 burst-forming unit-erythroid (BFU-E) frequencies peaked at day 4 (24.0+/-8.9%), with a marked decrease in BFU-E burst size as the cultures progressed. Time-course immunophenotypical profiles were characteristically erythroid with a decrease in CD34 expression (from 96.8+/-3.0% at day 0 to 0.8+/-0.8% at day 14), and a concomitant increase in the expression of erythroid-specific markers, CD36, glycophorin A (GpA) and CD71 (from 14.8+/-5.0%, 1.7+/-1.0% and 37.9+/-18.0% to 93.0+/-7.0%, 82.1+/-14.0% and 95.7+/-3.0%, respectively). Morphological studies revealed the presence of normoblasts with the complete absence of reticulocytes and mature erythrocytes after 14 days in culture. Once the culture conditions were optimized, we scaled down our culture model from 24-well plate (large-scale) to 96-well plate cultures (small-scale). We found that the small-scale cultures compared favorably with their large-scale counterpart in terms of erythroid progenitor cell proliferation and differentiation, particularly at low CD34(+) initiating cell doses. By using tumor necrosis factor-alpha (TNF-alpha), a known inhibitor of erythropoiesis, we validated our model system and showed a dose-dependent inhibition of erythroid differentiation with TNF-alpha in our cultures. Therefore, our results demonstrate a small-scale serum-free liquid culture model of erythropoiesis that is comparable with and complements our well-defined large-scale model. Our system would prove useful for screening the effects of exogenous factors on erythropoiesis in vitro.

Endolyn (CD164) modulates the CXCL12-mediated migration of umbilical cord blood CD133+ cells

Hematopoietic stem cell/hematopoietic progenitor cell (HSC/HPC) homing to specific microenvironmental niches involves interactions between multiple receptor ligand pairs. Although CXCL12/CXCR4 plays a central role in these events, CXCR4 regulators that provide the specificity for such cells to lodge and be retained in particular niches are poorly defined. Here, we provide evidence that the sialomucin endolyn (CD164), an adhesion receptor that regulates the adhesion of CD34+ cells to bone marrow stroma and the recruitment of CD34+CD38(lo/-) cells into cycle, associates with CXCR4. The class II 103B2 monoclonal antibody, which binds the CD164 N-linked glycan-dependent epitope or CD164 knockdown by RNA interference, significantly inhibits the migration of CD133+ HPCs toward CXCL12 in vitro. On presentation of CXCL12 on fibronectin, CD164 associates with CXCR4, an interaction that temporally follows the association of CXCR4 with the integrins VLA-4 and VLA-5. This coincides with PKC-zeta and Akt signaling through the CXCR4 receptor, which was disrupted on the loss of CD164 though MAPK signaling was unaffected. We therefore demonstrate a novel association among 3 distinct families of cell-surface receptors that regulate cell migratory responses and identify a new role for CD164. We propose that this lends specificity to the homing and lodgment of these cells within the bone marrow niche.

Blood vessel stem cells and wound healing

This article continues the Journal's "Scientific Surgery" series of leaders. The aim of the series, published throughout 2005, has been to highlight areas of bioscience that, while still largely confined to the experimental laboratory, may soon be brought into the clinical domain. In this month's paper Watt and Fox offer an up to date insight into the processes of tissue healing and suggest possible future therapeutic strategies.

Potential clinical applications using stem cells derived from human umbilical cord blood

There is an abundance of clinical applications using human umbilical cord blood (HUCB) as a source for stem cell populations. Other than haematopoietic progenitors, there are mesenchymal, endothelial stem cells and neuronal precursors, in varying quantities, that are found in human umbilical cord blood. These may be useful in diseases such as immune deficiency and autoimmune disorders. Considering issues of safety, availability, transplant methodology, rejection and side effects, it is contended that a therapeutic stem cell transplant, utilizing stem cells from HUCB, provides a reliable repository of early precursor cells that can be useful in a great number of diverse conditions. Drawbacks of relatively smaller quantities of mononucleated cells in one unit of cord blood can be mitigated by in-vitro expansion procedures, improved in-vivo signalling, and augmentation of the cellular milieu, while simultaneously choosing the appropriate transplantation site and technique for introduction of the stem cell graft.