Primitive hematopoietic stem and progenitor cells in human umbilical cord blood: an alternative source of transplantable cells

Intrathecal injection of human umbilical cord blood stem cells attenuates spinal cord ischaemic compromise in rats

OBECTIVES

Spinal cord ischaemia with resulting paraplegia remains a devastating and unpredictable complication after thoraco-abdominal aortic surgery. With the advent of stem cell therapy and its potential to induce nervous tissue regeneration processes, the interest in the use of these cells as a treatment for neurological disorders has increased. Human stem cells, derived from the umbilical cord, are one of the strong candidates used in cell therapy for spinal cord injury because of weak immunogenicity and ready availability. We sought to evaluate the use of human umbilical cord blood stem cells (HUCBSCs) to attenuate the neurological effects of spinal cord ischaemia induced by high thoracic aorta occlusion.

METHODS

Forty Wistar rats were randomized to receive intrathecal injection of 10 µl phosphate buffered saline (PBS) solution containing 1 × 10(4) HUCBSCs, 30 min before (Tpre group: n = 10) and 30 min after (Tpos group: n = 10) descending thoracic aorta occlusion by intraluminal balloon during 12 min. Control groups received only PBS solution (Cpre group: n = 10; and Cpos group: n = 10). During a 28-day observational period, motor function was assessed by a functional grading scale (Basso, Beattie and Bresnahan). Segments of thoracolumbar spinal cord specimens were analysed for histological and immunohistochemical assessment for detection and quantification of human haematopoietic cells (CD45(+)) and apoptosis (transferase-mediated deoxyuridine triphosphate-biotin nick-end labelling).

RESULTS

Overall mortality was 12 animals (30%). Therefore, the observational sample was composed of 28 animals. All groups showed similar incidence of paraplegia and mortality. The mean motor function scores showed no difference during time between the animals of each group, excepting for the Tpos group, which improved from 8.14 (±8.6) to 14.28 (±9.8) (P < 0.01). A treatment-by-time interaction was detected among animals that received HUCBSCs 30 min after ischaemia, with BBB scores higher from Days 14 to 28 compared with the first observational day with statistical difference (P = 0.01). Number of viable neurons was higher in the Tpos group (P = 0.14) and the incidence of apoptosis was lower in the same animals (P = 0.048), but showed no difference with its respective control. We confirmed the presence of CD45(+) cells 4 weeks after intrathecal injection in both therapeutic groups but mainly in the Tpos group.

CONCLUSIONS

Intrathecal transplantation of HUCBSCs is feasible, and it improved spinal cord function, when they were delivered 30 min after spinal cord ischaemia, in a model of endovascular descending thoracic aorta occlusion in rats. Human umbilical cord blood is one of the potentially useful sources of stem cells for therapy of spinal cord ischaemia.

Recovery of fine motor performance after ischemic damage to motor cortex is facilitated by cell therapy in the rhesus monkey

We investigated the efficacy on recovery of function following controlled cortical ischemia in the monkey of the investigational cell drug product, CNTO 0007. This drug contains a cellular component, human umbilical tissue-derived cells, in a proprietary thaw and inject formulation. Results demonstrate significantly better recovery of motor function in the treatment group with no difference between groups in the volume or surface area of ischemic damage, suggesting that the cells stimulated plasticity.

Neuroblast survival depends on mature vascular network formation after mouse stroke: role of endothelial and smooth muscle progenitor cell co-administration

Pro-angiogenic cell-based therapies constitute an interesting and attractive approach to enhancing post-stroke neurogenesis and decreasing neurological deficit. However, most new stroke-induced neurons die during the first few weeks after ischemia, thus impairing total recovery. Although the neovascularization process involves different cell types and various growth factors, most cell therapy protocols are based on the biological effects of single-cell-type populations or on the administration of heterogeneous populations of progenitors, namely human cord blood-derived CD34(+) cells, with scarce vascular progenitor cells. Tight cooperation between endothelial cells and smooth muscle cells/pericytes is critical for the development of functional neovessels. We hypothesized that neuroblast survival in stroke brain depends on mature vascular network formation. In this study, we injected a combination of endothelial progenitor cells (EPCs) and smooth muscle progenitor cells (SMPCs), isolated from human umbilical cord blood, into a murine model of permanent focal ischemia induced by middle cerebral artery occlusion. The co-administration of SMPCs and EPCs induced enhanced angiogenesis and vascular remodeling in the peri-infarct and infarct areas, where vessels exhibited a more mature phenotype. This activation of vessel growth resulted in the maintenance of neurogenesis and neuroblast migration to the peri-ischemic cortex. Our data suggest that a mature vascular network is essential for neuroblast survival after cerebral ischemia, and that co-administration of EPCs and SMPCs may constitute a novel therapeutic strategy for improving the treatment of stroke.

The effects of human umbilical cord blood transplantation in rats with experimentally induced spinal cord injury

OBJECT

Even though there have been many efforts to recover neuronal dysfunction following spinal cord injuries, there are limitations to the treatment of these injuries. The purpose of this laboratory investigation was to determine the clinical and neurophysiological effects of human umbilical cord blood (HUCB) transplantation in a rat hemisection model of spinal cord injury.

METHODS

In this study, experimental hemisection of the thoracic spinal cord was performed in rats. The rats were divided into 4 groups (6 rats in each group). One group of rats (Group 1) underwent thoracic laminectomy only. Rats in Group 2 underwent laminectomy and right hemisection of the thoracic spinal cord. Rats in Group 3 underwent right hemisection and implantation of freshly obtained HUCB on Day 0 postinjury. Rats in Group 4 underwent hemisection and implantation of freshly obtained HUCB on Day 4 postinjury. Clinical evaluations of rat motor function included the following: neurological examination, Rotarod performance, and inclined plane tests. Rats also underwent reflex evaluation.

RESULTS

The neurological examinations revealed that the frequency of plegic rats was 70.8% at the beginning of the study across all 4 groups; this value decreased to 20.8% by the end of the study. The percentage of rats with a normal examination increased from 25% to 50%. The results of Rotarod performance and 8-week inclined plane performance tests showed statistical significance (p < 0.05) in an overall group comparison across all time points. At the end of the 8 weeks, a statistically significant difference was found in the inclined plane test results between rats in Groups 1 and 2. There were no statistically significant differences between Groups 1, 3, and 4 (p < 0.05). When the reflex responses of the hemisectioned sides were compared, statistically significant differences were detected between groups (p < 0.05). All groups were significantly different with regard to the right-side reflex response score (p < 0.05). Spinal cord preparations of rats in all groups were examined for histopathological changes.

CONCLUSIONS

Human umbilical cord blood is stem cell rich and easily available, and it carries less risk of inducing a graft-versus-host reaction in the recipient. Human umbilical cord blood serum is also noted to contain stem cell–promoting factors, which is why cell isolation was not used in this study. Freshly obtained cord blood was also used because storage of cord blood has been reported to have some negative effects on stem cells. Transplantation of freshly obtained HUCB into the hemisectioned spinal cord experimental model demonstrated clinical and neurophysiological improvement.

Human umbilical cord blood treatment in a mouse model of ALS: optimization of cell dose

Background

Amyotrophic Lateral Sclerosis (ALS) is a multicausal disease characterized by motor neuron degeneration in the spinal cord and brain. Cell therapy may be a promising new treatment for this devastating disorder. We recently showed that a single low dose (10⁶ cells) of mononuclear human umbilical cord blood (MNC hUCB) cells administered intravenously to G93A mice delayed symptom progression and modestly prolonged lifespan. The aim of this pre-clinical translation study is to optimize the dose of MNC hUCB cells to retard disease progression in G93A mice. Three different doses of MNC hUCB cells, 10×10⁶, 25×10⁶ and 50×10⁶, were administered intravenously into pre-symptomatic G93A mice. Motor function tests and various assays to determine cell effects were performed on these mice.

Methodology/Principal Findings

Our results showed that a cell dose of 25×10⁶ cells significantly increased lifespan of mice by 20–25% and delayed disease progression by 15%. The most beneficial effect on decreasing pro-inflammatory cytokines in the brain and spinal cord was found in this group of mice. Human Th2 cytokines were found in plasma of mice receiving 25×10⁶ cells, although prevalent human Th1 cytokines were indicated in mice with 50×10⁶ cells. High response of splenic cells to mitogen (PHA) was indicated in mice receiving 25×10⁶ (mainly) and 10×10⁶ cells. Significantly increased lymphocytes and decreased neutrophils in the peripheral blood were found only in animals receiving 25×10⁶ cells. Stable reduction in microglia density in both cervical and lumbar spinal cords was also noted in mice administered with 25×10⁶ cells.

Conclusions/Significance

These results demonstrate that treatment for ALS with an appropriate dose of MNC hUCB cells may provide a neuroprotective effect for motor neurons through active involvement of these cells in modulating the host immune inflammatory system response.

Therapeutic potentials of human embryonic stem cells in Parkinson's disease

The loss of dopaminergic neurons of the substantia nigra is the pathological hallmark characteristic of Parkinson's disease (PD). The strategy of replacing these degenerating neurons with other cells that produce dopamine has been the main approach in the cell transplantation field for PD research. The isolation, differentiation, and long-term cultivation of human embryonic stem cells and the therapeutic research discovery made in relation to the beneficial properties of neurotrophic and neural growth factors has advanced the transplantation field beyond dopamine-producing cells. The present review addresses recent advances in human embryonic stem cell experimentation in relation to treating PD, as well as cell transplantation techniques in conjunction with alternative therapeutics.

Isolation of stem cells from human umbilical cord blood

Umbilical cord blood (UCB) is gaining more prominence in recent times as a source of non-embryonic multipotent stem cells. Global annual human birth rate (100 million) presents UCB as the largest non-controversial stem cell source, with an added advantage of naive immune status. Cord blood stem cells are routinely utilized in stem cell transplantation in leukemia patients and carry huge potential to treat other human diseases with less concern of rejection. Because UCB contains low number of stem cells, their use is associated with significant delays in engraftment of neutrophils and platelets. Development of reliable methods for isolation and expansion of cord blood stem cells is critical for consequent clinical application. The focus of this chapter is to review the methods currently used by different research groups and to recommend an isolation protocol that yields optimal number of UCB stem cells.

The use of hemopoietic stem cells derived from human umbilical cord blood to promote restoration of spinal cord tissue and recovery of hindlimb function in adult rats

OBJECT

The use of human umbilical cord blood (HUCB) cells has been reported to improve functional recovery in cases of central nervous system injuries such as stroke, traumatic brain injury, and spinal cord injury (SCI). The authors investigated the effects of hemopoietic stem cells that were derived from HUCB and transplanted into the injured spinal cords of rats.

METHODS

One week after injury, an HUCB fraction enriched in CD34-positive cells was transplanted into the experimental group. In control animals, vehicle (Matrigel) was transplanted. Recovery of motor functions was assessed using the Basso-Beattie-Bresnahan Locomotor Scale, and immunohistochemical examinations were performed. Cells from HUCB that were CD34 positive improved functional recovery, reduced the area of the cystic cavity at the site of injury, increased the volume of residual white matter, and promoted the regeneration or sparing of axons in the injured spinal cord. Immunohistochemical examination revealed that transplanted CD34-positive cells survived in the host spinal cord for at least 3 weeks after transplantation but had disappeared by 5 weeks. The transplanted cells were not positive for neural markers, but they were positive for hemopoietic markers. There was no evidence of an immune reaction at the site of injury in either group.

CONCLUSIONS

These results suggest that transplantation of a CD34-positive fraction from HUCB may have therapeutic effects for SCI. The results of this study provide important preclinical data regarding HUCB stem cell-based therapy for SCI.

Umbilical cord blood-derived stem cells and brain repair

Human umbilical cord blood (HUCB) is now considered a valuable source for stem cell-based therapies. HUCB cells are enriched for stem cells that have the potential to initiate and maintain tissue repair. This potential is especially attractive in neural diseases for which no current cure is available. Furthermore, HUCB cells are easily available and less immunogenic compared to other sources for stem cell therapy such as bone marrow. Accordingly, the number of cord blood transplants has doubled in the last year alone, especially in the pediatric population. The therapeutic potential of HUCB cells may be attributed to inherent ability of stem cell populations to replace damaged tissues. Alternatively, various cell types within the graft may promote neural repair by delivering neural protection and secretion of neurotrophic factors. In this review, we evaluate the preclinical studies in which HUCB was applied for treatment of neurodegenerative diseases and for traumatic and ischemic brain damage. We discuss how transplantation of HUCB cells affects these disorders and we present recent clinical studies with promising outcome.

Transplantation of human umbilical cord blood cells in the repair of CNS diseases

Cell transplantation therapies have been used to treat certain neurodegenerative diseases such as Parkinson's and Huntington's disease. However, ethical concerns over the use of fetal tissues, and the inherent complexities of standardising the procurement, processing and transplantation methods of this tissue, have prompted the search for a source of cells that have less ethical stigmatisations, are readily available and can be easily standardised. Several sources of human cells that meet these principles have been under investigation. Cells from human umbilical cord blood (HUCB) are one source that is consistent with these principles; therefore, they have become of great interest in the field of cellular repair/replacement for the treatment of CNS diseases and injury. This review will focus on the advantages of HUCB cells as a source for cellular transplantation therapies, recent studies that have examined the potential of these cells in vitro to be directed towards neural phenotypes, and in vivo studies that have investigated the functional recovery of animals in a number of models of CNS injury and disease following administration of HUCB cells.

Intraspinal transplantation of CD34+ human umbilical cord blood cells after spinal cord hemisection injury improves functional recovery in adult rats

The present study was designed to compare the functional outcome of the intraspinal transplantation of CD34+ human umbilical cord blood (CB) cells with that of human bone marrow stromal (BMS) cells in adult rats with spinal cord injury. Sixty adult Wistar rats were subjected to left spinal cord hemisection, and then divided into three groups randomly. The control group received an injection of PBS without cells, while the two other groups of rats received a transplantation of 5 x 10(5) CD34+ CB or BMS cells, respectively. Functional outcome was measured using the modified Tarlov score at days 1, 7, 14, 21, and 28 after transplantation. A statistically significant improvement in functional outcome and survival rate in the experimental groups of rats was observed compared with the control group. Rats that received CD34+ CB cells achieved a better improvement in functional score than those that received BMS cells at days 7 and 14 after transplantation. Histological evaluation revealed that bromodeoxyuridine (BrdU)-labeled CD34+ CB and BMS cells survived and migrated into the injured area. Some of these cells expressed glial fibriliary acidic protein (GFAP) or neuronal nuclear antigen (NeuN). Our data demonstrate for the first time that intraspinal transplantation of human CD34+ CB cells provides benefit in function recovery after spinal cord hemisection in rats and suggest that CD34+ CB cells may be an excellent choice of cells as routine starting material of allogenic and autologous transplantations for the treatment of spinal cord injury.

SDF-1α/CXCL12 enhances retroviral-mediated gene transfer into immature subsets of human and murine hematopoietic progenitor cells

Genetic modification of hematopoietic stem and progenitor cells has the potential to treat diseases affecting blood cells. Oncoretroviral vectors have been used for gene therapy; however, clinical success has been limited in part by low gene transfer efficiencies. We found that the presence of stromal-derived factor 1 (SDF-1alpha)/CXCL12 during retroviral transduction significantly enhanced, in a dose-dependent fashion, gene transfer into immature subsets of high proliferative human and murine hematopoietic progenitor cells. Murine mononuclear bone marrow cells and purified c-Kit(+)Lin(-) bone marrow cells were prestimulated and transduced with the bicistronic retroviral vector MIEG3 on Retronectin-coated surfaces in the presence and absence of SDF-1. SDF-1 enhanced gene transduction of murine bone marrow and c-Kit(+)Lin(-) cells by 35 and 29%, respectively. Moreover, SDF-1 enhanced transduction of progenitors in these populations by 121 and 107%, respectively. SDF-1 also enhanced transduction of human immature subsets of high proliferative progenitors present in either nonadherent mononuclear or CD34(+) umbilical cord blood cells. Transduction of hematopoietic progenitors was further increased by preloading Retronectin-coated plates with retrovirus using low-speed centrifugation followed by increasing cell-virus interactions through brief centrifugation during the transduction procedure. These results may be of clinical relevance.

Human umbilical cord blood stem cells infusion in spinal cord injury: engraftment and beneficial influence on behavior

The use of human umbilical cord blood (hUCB)--a rich source of nonembryonic or adult stem cells--has recently been reported to ameliorate behavioral consequences of stroke. In this study, we tested whether human cord blood leukocytes also ameliorate behavioral impairments of spinal cord injury. Rats were divided into five groups: (1) laminectomy (without spinal cord injury) only; (2) laminectomy + cord blood infusion; (3) spinal cord injury + cord blood infused 1 day post injury; (4) spinal cord injury + cord blood infused 5 days post injury; and (5) spinal cord injury only. Spinal cord injury was induced by compressing the spinal cord for 1 min with an aneurysm clip calibrated to a closing pressure of 55 g. Open-field behavior was assessed 1, 2, and 3 weeks after intravenous injection of prelabeled human cord blood cells. Open-field test scores of spinal cord injured rats treated with human cord blood at 5 days were significantly improved as compared to scores of rats similarly injured but treated at day 1 as well as the otherwise untreated injured group. The results suggest that cord blood stem cells are beneficial in reversing the behavioral effects of spinal cord injury, even when infused 5 days after injury. Human cord blood-derived cells were observed in injured areas, but not in noninjured areas, of rat spinal cords, and were never seen in corresponding areas of spinal cord of noninjured animals. The results are consistent with the hypothesis that cord blood-derived stem cells migrate to and participate in the healing of neurological defects caused by traumatic assault.

Profiling of differentially expressed apoptosis-related genes by cDNA arrays in human cord blood CD34+ cells treated with etoposide

OBJECTIVE

Understanding the molecular events that contribute to survival of and drug-induced apoptosis in hematopoietic stem and progenitor cells (HSC/P) can have impact on more rational approaches to blood cancer therapeutic design, as well as on strategies to minimize toxic side effects of chemotherapeutic drugs. Here we sought to systematically evaluate the basic molecular components and main pathways that govern and mediate cellular response initiated within human CD34(+) cells to etoposide-induced apoptosis.

MATERIALS AND METHODS

Human CD34(+) cells were isolated from umbilical cord blood (CB) and expanded in vitro. Expression of apoptosis-related genes in the control and etoposide treated cells was determined using cDNA array and quantitative real-time RT-PCR.

RESULTS

We identified a set of apoptosis-related genes expressed in highly purified normal human CB CD34(+) cells and determined how the expression of these genes changed in response to etoposide treatment. In addition, TRAIL does not induce apoptosis of normal human CD34(+) cells, and it has no cytotoxic effect on human CD34(+) cells that are undergoing apoptosis in response to growth factor withdrawal. This may be due to upregulation of cytotoxic receptors as well as the decoy receptor for TRAIL, and c-FLIP.

CONCLUSION

p53, c-Myc, and BAFF pathways are main pathways utilized by CD34(+) cells to arrest cell-cycle progression at multiple checkpoints, to halt proliferation, and to induce apoptosis as part of their cellular response to etoposide. Multiple known pro-survival and pro-apoptotic pathways are simultaneously activated in etoposide-treated CD34(+) cells. Also, TRAIL, used alone or in concert with chemotherapeutic drugs, may be of use as a safe blood cancer therapeutic with no or low toxicity for HSC/P.

Human umbilical cord blood (HUCB) cells for central nervous system repair

Cellular therapy is a compelling and potential treatment for certain neurological and neurodegenerative diseases as well as a viable treatment for acute injury to the spinal cord and brain. The hematopoietic system offers alternative sources for stem cells compared to those of fetal or embryonic origin. Bone marrow stromal and umbilical cord cells have been used in pre-clinical models of brain injury, directed to differentiate into neural phenotypes, and have been related to functional recovery after engraftment in central nervous system (CNS) injury models. This paper reviews the advantages, utilization and progress of human umbilical cord blood (HUCB) cells in the neural cell transplantation and repair field.

Current understanding of stem cell mobilization: the roles of chemokines, proteolytic enzymes, adhesion molecules, cytokines, and stromal cells

Mobilization of hematopoietic stem and progenitor cells from the bone marrow into the circulation by repetitive, daily stimulations with G-CSF alone, or in combination with cyclophosphamide, is increasingly used clinically; however, the mechanism is not fully understood. Moreover, following mobilization stem cells also home back to the bone marrow, suggesting that stem cell release/mobilization and homing are sequential events with physiological roles. Previously, a role for cytokines such as G-CSF and SCF, and adhesion molecules such as VLA-4 and P/E selectins, was determined for stem cell mobilization. Recent results using experimental animal models and samples from clinical mobilization protocols demonstrate major involvement of chemokines such as stromal derived factor-1 (SDF-1) and IL-8, as well as proteolytic enzymes such as elastase, cathepsin G, and various MMPs in the mobilization process. These results will be reviewed together with the central roles of SDF-1 and CXCR4 interactions in G-CSF or G-CSF in combination with cyclophosphamide-induced mobilization. Furthermore, the central role of this chemokine in stem cell homing to the bone marrow as well as retention of undifferentiated cells within this tissue will also be discussed.

Applications of developmental biology to medicine and animal agriculture

With the complete sequence of the human genome expected by winter 2001, genomic-based drug discovery efforts of the pharmaceutical industry are focusing on finding the relatively few therapeutically useful genes from among the total gene set. Methods to rapidly elucidate gene function will have increasing value in these investigations. The use of model organisms in functional genomics has begun to be recognized and exploited and is one example of the emerging use of the tools of developmental biology in recent drug discovery efforts. The use of protein products expressed during embryo-genesis and the use of certain pluripotent cell populations (stem cells) as candidate therapeutics are other applications of developmental biology to the treatment of human diseases. These agents may be used to repair damaged or diseased tissues by inducing or directing developmental programs that recapitulate embryonic processes to replace specialized cells. The activation or silencing of embryonic genes in the disease state, particularly those encoding transcription factors, is another avenue of exploitation. Finally, the direct drug-induced manipulation of embryonic development is a unique application of developmental biology in animal agriculture.

Engraftment of primates with G-CSF mobilized peripheral blood CD34+ progenitor cells expanded in G-CSF, SCF and MGDF decreases the duration and severity of neutropenia

We used a primate model of autologous peripheral blood progenitor cell (PBPC) transplantation to study the effect of in vitro expansion on committed progenitor cell engraftment and marrow recovery after transplantation. Four groups of baboons were transplanted with enriched autologous CD34+ PBPC collected by apheresis after five days of G-CSF administration (100 microg/kg/day). Groups I and III were transplanted with cryopreserved CD34+ PBPC and Groups II and IV were transplanted with CD34+ PBPC that had been cultured for 10 days in Amgen-defined (serum free) medium and stimulated with G-CSF, megakaryocyte growth and development factor (MGDF), and stem cell factor each at 100 etag/ml. Group III and IV animals were administered G-CSF (100 microg/kg/day) and MGDF (25 microg/kg/day) after transplant, while animals in Groups I and II were not. For the cultured CD34+ PBPC from groups II and IV, the total cell numbers expanded 14.4 +/- 8.3 and 4.0 +/- 0.7-fold, respectively, and CFU-GM expanded 7.2 +/- 0.3 and 8.0 +/- 0.4-fold, respectively. All animals engrafted. If no growth factor support was given after transplant (Groups II and I), the recovery of WBC and platelet production after transplant was prolonged if cells had been cultured prior to transplant (Group II). Administration of post-transplant G-CSF and MGDF shortened the period of neutropenia (ANC < 500/microL) from 13 +/- 4 (Group I) to 10 +/- 4 (Group III) days for animals transplanted with non-expanded CD34+ PBPC. For animals transplanted with ex vivo-expanded CD34+ PBPC, post-transplant administration of G-CSF and MGDF shortened the duration of neutropenia from 14 +/- 2 (Group II) to 3 +/- 4 (Group IV) days. Recovery of platelet production was slower in all animals transplanted with expanded CD34+ PBPC regardless of post-transplant growth factor administration. Progenitor cells generated in vitro can contribute to early engraftment and mitigate neutropenia when growth factor support is administered post-transplant. Thrombocytopenia was not decreased despite evidence of expansion of megakaryocytes in cultured CD34+ populations.