Umbilical cord blood for allogeneic transplantation in children and adults

Effect of Mesenchymal Stem Cell-derived Microvesicles on Megakaryocytic Differentiation of CD34+ Hematopoietic Stem Cells

Purpose: Mesenchymal stem cells (MSCs) release hematopoietic cytokines, growth factors, and Microvesicles (MVs) supporting the hematopoietic stem cells (HSCs). MVs released from various cells, playing a crucial role in biological functions of their parental cells. MSC-derived MVs contain microRNAs and proteins with key roles in the regulation of hematopoiesis. Umbilical cord blood (UCB) is a source for transplantation but the long-term recovery of platelets is a main problem. Therefore, we intend to show that MSC-MVs are able to improve the differentiation of UCB-derived CD34⁺ cells to megakaryocyte lineage.

Methods: In this descriptive study, MSCs were cultured in DMEM to collect the culture supernatant, which was ultracentrifuged for the isolation of MVs. HSCs were isolated from UCB using MACS method and cultured in IMDM supplemented with cytokines and MVs in three different conditions. Megakaryocyte differentiation was evaluated through the expression of specific markers and genes after 72 hours, and the data was analyzed by t test (P<0.05).

Results: The expression of specific megakaryocyte markers (CD41 and CD61) in the presence of different concentrations of MSC-MVs did not show any significant difference. Also, the expression of specific genes of megakaryocyte lineage was compared with control group. The expression of GATA2 and c-Mpl was significantly increased, GATA1 was not significantly decreased, and FLI1 was significantly decreased.

Conclusion: MSC-MVs could improve the expression of specific megakaryocyte genes; however, there was no significant expression of CD markers. Further studies, including the evaluation of late stages of megakaryocyte differentiation, are required to evaluate platelet production and shedding

Effect of intracameral human cord blood-derived stem cells on lasered rabbit trabecular meshwork

BACKGROUND

This study aimed to investigate the effect of intracameral human cord blood stem cells on lasered rabbit trabecular meshwork.

METHODS

Immediately following diode laser application to the trabecular meshwork, human cord blood stem cells were injected intracamerally, in one eye of 12 albino rabbits. The other eye of ten rabbits was lasered controls and two eyes were normal controls. Rabbits were killed after 4, 8 and 12 weeks.

RESULTS

Lasered control rabbit eyes showed significant disruption of trabecular architecture, loss and pleomorphism of trabecular endothelial cells and progressive narrowing of trabecular spaces till 12 weeks. In contrast, lasered eyes, concurrently injected with human cord blood stem cells, showed relatively preserved endothelial cellularity and structure of the trabecular meshwork, at all time points. Human CD34- and CD44-positive cells were identified in 7/8 eyes treated with stem cells, at 4 and 8 weeks, and 2 of 3 at 12 weeks. Many PKH26-labeled human cord blood cells were visible throughout the trabecular area at 4 weeks. They gradually decreased in number by 8 weeks, and at 12 weeks, they appeared to be oriented along trabecular beams.

CONCLUSIONS

There was a relative preservation of cellularity and architecture of the trabecular meshwork in eyes injected with human cord blood stem cells, as compared to lasered control eyes up to 12 weeks, without significant inflammation. This suggests a probable role for such stem cells in eyes with glaucoma, having trabecular dysfunction.

Long-term results of a pilot study evaluating hyperbaric oxygen therapy to improve umbilical cord blood engraftment

Umbilical cord blood (UCB) transplantation is a promising option for hematopoietic stem cell transplantation in patients with hematologic malignancies who lack an HLA-matched sibling or well-matched unrelated donor; however, it has a higher incidence of delayed or failed engraftment because cell doses are low and bone marrow homing is inefficient. We have demonstrated that pre-treating irradiated immune-deficient mice with hyperbaric oxygen (HBO) prior to UCB CD34+ cell transplantation lowered host systemic erythropoietin (EPO) and improved UCB CD34+ cell homing and engraftment. These findings suggested that EPO-EPO-R signaling plays a role in UCB CD34+ homing and engraftment. In a pilot clinical trial, we showed that recipients of HBO therapy prior to UCB cell infusion had reduced systemic EPO, which was associated with improved kinetics of blood count recovery. Although early clinical outcomes at day 100 were encouraging, with improved overall survival, the long-term effects of HBO therapy on UCB-transplanted patients were not evaluated. In this study, we examined the long-term outcome of patients in our pilot study, compared with a historic control group, and correlated their clinical outcomes to serum EPO response to HBO. While 50% of HBO-treated patients received single UCB units, ~ 90% of the control patients received double UCB units. Although HBO patients had much better rates of survival at 6 months, their 1-year survival did not significantly differ from the control group. HBO-treated patients had on average lower relapse and non-relapse mortality rates, and less chronic graft versus host disease (GVHD), but had increased acute GVHD. However, these differences were not statistically significant, probably because of the small sample size. In the HBO-treated cohort, immune reconstitution analysis showed significant improvement in early B cell recovery, with a trend toward improvement in early NK cell recovery. When we evaluated the ratio of 8 h to baseline EPO levels, we found a non-significant trend toward lower EPO values in those who neither relapsed nor died by 1 year, compared to those who died or relapsed. This result suggests that EPO response to HBO may be associated with better outcomes. Disease progression-free survival was also improved in those who had more than 80% reduction in EPO levels in response to HBO. Our study highlights the long-term safety of HBO therapy when used prior to UCB transplantation. Future UCB transplant patients who receive HBO should have their serum EPO response measured, as it may be a marker of relapse/mortality.

Advances of Stem Cell Therapeutics in Cutaneous Wound Healing and Regeneration

Cutaneous wound healing is a complex multiple phase process, which overlaps each other, where several growth factors, cytokines, chemokines, and various cells interact in a well-orchestrated manner. However, an imbalance in any of these phases and factors may lead to disruption in harmony of normal wound healing process, resulting in transformation towards chronic nonhealing wounds and abnormal scar formation. Although various therapeutic interventions are available to treat chronic wounds, current wound-care has met with limited success. Progenitor stem cells possess potential therapeutic ability to overcome limitations of the present treatments as it offers accelerated wound repair with tissue regeneration. A substantial number of stem cell therapies for cutaneous wounds are currently under development as a result of encouraging preliminary findings in both preclinical and clinical studies. However, the mechanisms by which these stem cells contribute to the healing process have yet to be elucidated. In this review, we emphasize on the major treatment modalities currently available for the treatment of the wound, role of various interstitial stem cells and exogenous adult stem cells in cutaneous wound healing, and possible mechanisms involved in the healing process.

Evaluation of human cord blood CD34+ hematopoietic stem cell differentiation to megakaryocyte on aminated PES nanofiber scaffold compare to 2-D culture system

CONTEXT

Recently, umbilical cord blood (UCB) has been recognized as a suitable potential source of hematopoietic stem/progenitor cells (HSPCs) for transplantation. Lengthy thrombocytopenia after UCB transplantation is a major problem because of insufficient megakaryocyte (Mk) progenitors, which results in delayed platelet recovery. Frequent allogenic platelet transfusion leads to resistance to platelet units and higher risk of transmission of pathogenic agent.

OBJECTIVE

Ex vivo expansion of HSPCs and their differentiation to Mk progenitors on aminated PES nanofiber could lead to faster platelet recovery after UCB transplantation.

MATERIALS AND METHODS

CD34 cells were positively enriched using the MidiMACS system. CD34(+) cells were seeded onto conventional culture and aminated PES scaffold. The proliferation of CD34(+) cells, and also their differentiation into Mk progenitors, were evaluated. We used the flow cytometric method for analyzing CD41 and CD61 markers and real-time PCR for the expression level of transcription factors, as NF-E2 and GATA-1.

RESULTS

This study indicated increased CD34(+) cell population in aminated PES compared to the conventional system. After differentiation, the amount of CD41/CD61-expressing cells and the quantity of NF-E2 expression level increased in the aminated PES versus the 2-D system. The quantity of GATA-1 expression level was reduced on CD41/CD61(+) cells compared to CD34(+) cells, with no difference between the aminated PES and the conventional system.

DISCUSSION

Aminated PES nanofiber could have more effect on the proliferation of CD34(+) cells and Mk differentiation than the conventional culture.

CONCLUSION

Injection of the expanded cells and differentiated Mk progenitors, along with the transplantation of UCB stem cells might accelerate recovery of platelets and decrease the period of thrombocytopenia after transplantation.

Migration of human umbilical cord blood cells into rat liver

BACKGROUND AND OBJECTIVES

Cell therapy provides an effective strategy for the treatment of an impaired liver. Human umbilical cord blood progenitor cells have the potential to differentiate into hepatocytes. Progenitor cells transplanted into the spleen could migrate directly into the liver through portal circulation. To track migration of human umbilical cord blood progenitor cells in cirrhotic rat liver after intrasplenic transplantation and to prove the possibility similar behavior of human umbilical cord blood nucleated cells in humans.

METHODS AND RESULTS

Umbilical cord blood samples from full-term deliveries will be collected after obtaining an informed consent from the mother. The collection procedure will be conducted after completion of delivery and will not interfere with the normal obstetric procedures. Adult male Sprague Dawley rats were subjected to liver cirrhosis by intraperitoneal injection of thioacetamide. Cirrhotic rats were treated with human umbilical cord blood nucleated cells by intra-splenic transplantation. Migration of intrasplenic transplanted human umbilical cord blood cells to the liver was successfully documented with Immunohistochemistry. The liver and spleen from recipient animals were removed. Histopathological and immunohistochemical analysis were performed 20 weeks after intrasplenic injection of the cells. Intrasplenically injected cells migrate to the liver of recipient animals.

CONCLUSIONS

Human cord blood nucleated cells have the potential to differentiate into hepatocytes and substantially improve the histology and function of the cirrhotic liver in rats. Relocation into liver after intrasplenic transplantation could be detected by immunohistochemistry. Transdifferentiated cells could be efficiently stained with antihuman hepatocytes.

Applications of stem cells in interdisciplinary dentistry and beyond: an overview

In medicine stem cell–based treatments are being used in conditions like Parkinson's disease, neural degeneration following brain injury, cardiovascular diseases, diabetes, and autoimmune diseases. In dentistry, recent exciting discoveries have isolated dental stem cells from the pulp of the deciduous and permanent teeth, from the periodontal ligament, and an associated healthy tooth structure, to cure a number of diseases. The aim of the study was to review the applications of stem cells in various fields of dentistry, with emphasis on its banking, and to understand how dental stem cells can be used for regeneration of oral and non-oral tissues conversely. A Medline search was done including the international literature published between 1989 and 2011. It was restricted to English language articles and published work of past researchers including in vitro and in vivo studies. Google search on dental stem cell banking was also done. Our understanding of mesenchymal stem cells (MSC) in the tissue engineering of systemic, dental, oral, and craniofacial structures has advanced tremendously. Dental professionals have the opportunity to make their patients aware of these new sources of stem cells that can be stored for future use, as new therapies are developed for a range of diseases and injuries. Recent findings and scientific research articles support the use of MSC autologously within teeth and other accessible tissue harvested from oral cavity without immunorejection. A future development of the application of stem cells in interdisciplinary dentistry requires a comprehensive research program.

Effect of human parathyroid hormone on hematopoietic progenitor cells in NOD/SCID mice co-transplanted with human cord blood mononuclear cells and mesenchymal stem cells

PURPOSE

We evaluated the effect of human parathyroid hormone (hPTH) on the engraftment and/or in vivo expansion of hematopoietic stem cells in an umbilical cord blood (UCB)-xenotransplantation model. In addition, we assessed its effect on the expression of cell adhesion molecules.

MATERIALS AND METHODS

Female NOD/SCID mice received sublethal total body irradiation with a single dose of 250 cGy. Eighteen to 24 hours after irradiation, 1 × 10(7) human UCB-derived mononuclear cells (MNCs) and 5 × 10(6) human UCB-derived mesenchymal stem cells (MSCs) were infused via the tail vein. Mice were randomly divided into three groups: Group 1 mice received MNCs only, Group 2 received MNCs only and were then treated with hPTH, Group 3 mice received MNCs and MSCs, and were treated with hPTH.

RESULTS

Engraftment was achieved in all the mice. Bone marrow cellularity was approximately 20% in Group 1, but 70-80% in the hPTH treated groups. Transplantation of MNCs together with MSCs had no additional effect on bone marrow cellularity. However, the proportion of human CD13 and CD33 myeloid progenitor cells was higher in Group 3, while the proportion of human CD34 did not differ significantly between the three groups. The proportion of CXCR4 cells in Group 3 was larger than in Groups 1 and 2 but without statistical significance.

CONCLUSION

We have demonstrated a positive effect of hPTH on stem cell proliferation and a possible synergistic effect of MSCs and hPTH on the proportion of human hematopoietic progenitor cells, in a xenotransplantation model. Clinical trials of the use of hPTH after stem cell transplantation should be considered.

Embryonic development of hematopoietic stem cells: implications for clinical use

Hematopoietic stem cell (HSC) transplantation is an important treatment modality for hematological malignancies or to correct congenital immunodeficiency disorders. Several stem cell sources are currently applied clinically, with a recent increased application of umbilical cord blood. The low number of HSCs available, particularly in umbilical cord blood, is a limiting factor, and different lines of research are ongoing to circumvent this issue. In this review, we will describe the research strategies developed to expand adult HSCs in vitro and to generate new HSCs from pluripotent stem cell lines. We will also discuss the importance of studying the embryonic microenvironment since it allows both generation and extensive expansion of HSCs. Understanding the mechanisms that underlie HSC production, self-renewal and differentiation is necessary for the establishment of optimal in vitro HSC cultures, where a limitless and manipulatable resource of HSCs would be available for both clinical and fundamental research.

Ex vivo expansion of umbilical cord blood: where are we?

Since the first successful clinical use of umbilical cord blood (UCB) in 1988, UCB grafts have been used for over 20,000 patients with both malignant and non-malignant diseases. UCB has several practical advantages over other transplantable graft sources. For example, the ease of procurement, the absence of donor risks, the reduced risk of transmissible infections, and the availability for immediate use make UCB an appealing graft choice. However, UCB grafts suffer from a few limitations related to the limited cell dose available for transplantation in each UCB unit and to defects in UCB stem cell homing. These limitations lead to increased post-transplant complications. In this review, we focus on the issue of limited cell dose in UCB units and discuss the possible approaches to overcome this limitation. We also summarize the various cellular pathways that have been explored to expand UCB units.

Stem cell mediated tooth regeneration: new vistas in dentistry

The generation of dental structures and/or entire teeth in the laboratory depends upon the manipulation of stem cells and requires a synergy of all cellular and molecular events that finally lead to the formation of tooth-specific hard tissues, dentin and enamel. This review focuses on the different sources of stem cells that have been used for making teeth in vitro and their relative efficiency. Embryonic, post-natal and adult stem cells were assessed and proved to possess an enormous regenerative potential, but their application in dental practice is still limited due to various parameters that are not yet under control such as the high risk of rejection, cell behaviour, long tooth eruption period, appropriate crown morphology and suitable colour. Nevertheless, the development of biological approaches for dental reconstruction using stem cells is promising and remains one of the greatest challenges in the dental field.

The rationale behind collecting umbilical cord blood

Umbilical cord blood (UCB) is an increasingly important and rich source of stem cells. These cells can be used for the treatment of many diseases, including cancers and immune and genetic disorders. For patients for whom no suitable related donor is available, this source of hematopoietic stem cells offers substantial advantages, notably the relative ease of procurement, the absence of risk to the donor, the small likelihood of transmitting clinically important infections, the low risk of severe graft-versus-host disease (GVHD) and the rapid availability of placental blood for transplantation centers. Even though almost 80 diseases are treatable with cord blood stem cells, 97 percent of cord blood is still disposed of after birth and lost for patients in need! To improve availability of stem cells to a broader community, efforts should be undertaken to collect cord blood and expectant parents should be properly informed of their options with regard to cord blood banking.

Efficient intracytoplasmic labeling of human umbilical cord blood mesenchymal stromal cells with ferumoxides

Mesenchymal stromal cells (MSCs) are multipotent cells found in several adult tissues; they have the capacity to differentiate into mesodermal, ectodermal, and endodermal tissues in vitro. There have been several reports that MSCs have therapeutic effects in a variety of diseases. Therefore, using a cell labeling technique, monitoring their temporal and spatial migration in vivo, would be useful in the clinical setting. Magnetic resonance imaging (MRI)--tracking of superparamagnetic iron oxide (SPIO)-labeled cells--is a noninvasive technique for determining the location and migration of transplanted cells. In the present study, we evaluated the influence and toxicity of SPIO (ferumoxides) labeling on multiple differentiated MSCs. To evaluate the influence and toxicity of ferumoxides labeling on differentiation of MSCs, a variety of concentrations of ferumoxides were used for labeling MSCs. We found that the cytoplasm of adherent cells was effectively labeled at low concentrations of ferumoxides. Compared with unlabeled controls, the ferumoxides-labeled MSCs exhibited a similar proliferation rate and apoptotic progression. The labeled MSCs differentiated into osteoblasts and adipocytes in an identical fashion as the unlabeled cells. However, chondrogenesis and neurogenesis were inhibited at high concentrations of ferumoxides. Our results suggest the effective concentration for ferumoxides use in tracking MSCs.

Influence of human leucocyte antigen disparity and graft lymphocytes on allogeneic engraftment and survival after umbilical cord blood transplant in adults

The dose of graft-nucleated cells and CD34(+) haematopoietic progenitor cells are predictors of allogeneic engraftment and survival in umbilical cord blood (UCB) recipients. In this single institution prospective phase II trial, flow cytometric analyses of CD34(+) progenitor and lymphocyte populations in unmodified single unit human leucocyte antigen (HLA)-disparate UCB grafts infused into 31 consecutive adults (median age 41 years, range 20-64) receiving myeloablative conditioning were compared with clinical outcomes. Median infused UCB graft-nucleated cells and CD34(+) dose was 2.2 x 10(7)/kg and 1.2 x 10(5)/kg respectively. Day to absolute neutrophil count >/=0.5 x 10(9)/l with full donor chimerism averaged 27 d (range 12-41). Univariate analyses demonstrated that UCB graft-infused cell doses of CD34(+) (P = 0.015), CD3(+) (P = 0.024) and CD34(+)HLADR(+)CD38(+) progenitors (P = 0.043) correlated with neutrophil engraftment. This same analysis did not demonstrate a correlation between CD34(+) (P = 0.11), CD3(+) (P = 0.28) or CD34(+)HLADR(+)CD38(+) (P = 0.108) cell dose and event-free survival (EFS). High-resolution matching for HLA-class II (DRB1) resulted in improved EFS (P = 0.02) and decreased risk for acute graft-versus-host disease (GVHD) (P = 0.004). Early mortality (prior to post-transplant day +28) occurred in three patients, while 26 patients achieved myeloid engraftment. These results suggest that UCB graft matching at DRB1 is an important risk factor for acute GVHD and survival, while higher UCB graft cell doses of CD34(+), committed CD34(+) progenitors and CD3(+) T cells favourably influence UCB allogeneic engraftment.

Telomere length changes after umbilical cord blood transplant

BACKGROUND

The establishment of donor-derived hematopoiesis in the recipients of hematopoietic stem cell (HSC) transplants involves extensive proliferation and differentiation of HSCs. Data from long-term survivors of HSC transplants suggest that these transplanted HSCs may experience a debilitating replicative senescence. A significant posttransplant shortening of peripheral blood mononuclear cell (PBMNC) telomeres has been observed in both marrow transplant and peripheral blood progenitor cell transplant recipients. Similar studies have not been performed for umbilical cord blood (UCB) HSC transplants, which might be expected to exhibit increased posttransplant replicative potential due to their inherently greater telomere length.

STUDY DESIGN AND METHODS

Blood was obtained from donor-recipient pairs of allogeneic PBHSC transplant and UCB HSC transplant, both before transplant and at follow-up treatments (minimum 1 year after transplant) after engraftment. Telomere restriction fragment length (TRFL) analysis was performed on the blood samples. The mean TRFL and posttransplant changes in the mean TRFL were analyzed.

RESULTS

Measurements of telomere lengths in the PBMNCs of transplant patients revealed a significant net decrease in telomere length in all transplant recipients compared with their respective donors. Our results also revealed that the PBMNCs of umbilical cord stem cell transplant patients retain a significantly longer posttransplant telomere length.

CONCLUSION

The significantly longer telomeres observed in the allogeneic UCB HSC transplant recipients compared to the allogeneic PBHSC transplant recipients in our study may be indicative of a replicative advantage inherent in the use of UCB HSC for transplant.

Lack of isohemagglutinin production following minor ABO incompatible unrelated HLA mismatched umbilical cord blood transplantation

While immune hemolysis due to donor isohemagglutinin (IH) production often complicates minor ABO incompatible peripheral blood hematopoietic stem cell transplantation (PBSCT), it is not known if this occurs with umbilical cord blood transplantation (UCBT). We compared IH production and hemolysis following minor ABO allogeneic PBSCT and UCBT. We reviewed 24 ABO minor incompatible allogeneic PBSCTs and 14 ABO minor incompatible UCBTs. Patients were evaluated for donor-derived IH by reverse ABO grouping. Evaluation of hemolysis was based on clinical and laboratory findings of anemia associated with increased RBC transfusion need, concomitant with the appearance of donor-derived IH. Of the 24 ABO minor incompatible allogeneic PBSCTs, 15 produced donor-derived IH from 6 to 88 days following transplantation, with seven of 15 patients exhibiting clinically evident hemolysis. There was no significant difference in days to leukocyte engraftment or infused CD34 cells in patients with or without donor-derived IH. None of the 14 patients receiving ABO incompatible UCBTs showed evidence of donor-derived IH following transplantation with a median follow-up of 60 days. We conclude that donor IHs are not produced in patients undergoing minor ABO incompatible UCBTs suggesting fundamental immunologic differences between allogeneic PBSCT and UCBT.

A closed system for the clinical banking of umbilical cord blood

Umbilical cord blood (UCB) is a source of hematopoietic progenitor cells and is used as an alternative to the bone marrow or peripheral blood for treatment of several onco-hematological diseases. Because of the limited number of CD34+ hematopoietic stem cells present in UCB units and of the elevated costs of cryopreservation, it is of paramount importance to select the UCB units that are clinically useful before storage and optimize banking efficiency by designing reliable procedures to process and freeze the selected units. Among the different parameters characterizing UCB, nucleated cell (NC) and CD34+ cell content provides useful criteria to select UCB units since clinical data documented that the infused cell load (both NC and CD34+ cells) plays an important role in the successful outcome of transplants. By evaluating volume, CD34+ cell content, NC total amount, and NC density of 117 UCB units, we found a significant association between CD34+ cell content and NC density and total amount, indicating these parameters as useful to decide UCB clinical utility. Furthermore, we set up a fast procedure to process UCB units for storage. A system for NC separation and volume reduction of UCB samples in a dedicated, germ-free, closed circuit was developed, where plasma and red blood cells (RBC) depletion was obtained by sedimentation in the presence of a 3.5% Polygeline solution. By this separation system, both RBC depletion and high NC and CD34+ cell recoveries were achieved in 60 min, and the yield was comparable to the one obtained by other separation methods. Since Polygeline has been clinically used as a plasma expander and no toxic effects on patients were reported, the protocol can be applied in the large-scale banking of UCB.

Autocrine transforming growth factor-beta regulation of hematopoiesis: many outcomes that depend on the context

Transforming growth factor-beta (TGF-beta) is a pleiotropic regulator of all stages of hematopoieis. The three mammalian isoforms (TGF-beta1, 2 and 3) have distinct but overlapping effects on hematopoiesis. Depending on the differentiation stage of the target cell, the local environment and the concentration and isoform of TGF-beta, in vivo or in vitro, TGF-beta can be pro- or antiproliferative, pro- or antiapoptotic, pro- or antidifferentiative and can inhibit or increase terminally differentiated cell function. TGF-beta is a major regulator of stem cell quiescence, at least in vitro. TGF-beta can act directly or indirectly through effects on the bone marrow microenvironment. In addition, paracrine and autocrine actions of TGF-beta have overlapping but distinct regulatory effects on hematopoietic stem/progenitor cells. Since TGF-beta can act in numerous steps in the hematopoietic cascade, loss of function mutations in hematopoeitic stem cells (HSC) have different effects on hematopoiesis than transient blockade of autocrine TGF-beta1. Transient neutralization of autocrine TGF-beta in HSC has therapeutic potential. In myeloid and erythroid leukemic cells, autocrine TGF-beta1 and/or its Smad signals controls the ability of these cells to respond to various differentiation inducers, suggesting that this pathway plays a role in determining the cell fate of leukemic cells.

Cobblestone area measuring (CAM) assay: a new way of assessing the potential of human haemopoietic stem cells

A new in vitro way of scoring the potential (proliferative- differentiative) of human haemopoietic stem cells (HHSC) is presented. We have applied it in the investigation of HHSC behaviour in normal bone marrow specimens under culture conditions. This system describes a modification of some existing culture assays for primitive HHSC function, and proliferation of the cobblestone area forming cell (CAFC) was determined by counting the cobblestone areas (CA) produced every week. The main steps of the assay are: (a) culture of MNC fraction on pre-established fibroblastic confluent layers from the M2.10B4 mouse cell line; (b) weekly counting of CA over a period of 5 weeks; (c) weekly in situ observation of CA morphology; (d) enumeration of secondary progenitors per CA, in the 5th week. The CAM index, expressing the value of the CA kinetic line slope and the number of secondary progenitors per CA were evaluated as factors indicating HHSC proliferative and differentiative potential, respectively. This culture system has the potential to serve as an in vitro assay of human stem cell transplantation. It could be applied to evaluating the potential of HHSC contained in haemopoietic collections of diverse origin, only in combination with measurements of the starting number of CAFC.

Mesenchymal stem/progenitor cells developed in cultures from UC blood

Background Whether umbilical cord blood (UCB) serves as a source of mesenchymal stem/progenitor cells (MSPC) is controversial. MSPC are the best candidates for cellular therapy of orthopedic skeletal tissues. In order to explore the possibility of UCB as a useful source of MSPC, we identified, expanded in culture, and characterized MSPC from UCB harvests on a large scale. Methods Mononuclear cells isolated from UCB harvests (n=411) were cultured in media supplemented with 10% FBS. MSPC-like cells cultured from each UCB harvest were expanded ex vivo by successive subcultivation. UCB harvests with a more than 1000-fold expanding capacity (n=9) were examined for surface Ag phenotypes and in vitro differentiation potentials into osteogenic, chondrogenic and adipogenic lineages. Results Ninety-five out of a total of 411 UCB units (23.1%) generated MSPC-like cells during cultivation. Nine UCB units (2.2%) yielded MSPC with more than 1000-fold expansion capacity. These cells positively expressed MSPC-related Ag, but did not express myeloid, histocompatibility or endothelial Ag. These cells also possessed multiple capacities for osteogenic, chondrogenic and adipogenic differentiation. Discussion Although the incidence of UCB harvests producing MSPC in culture was low, some of them showed a more than 1000-fold expanding capacity, which is enough in cell numbers to be an allogeneic source for cellular therapy. Our results may encourage the use of UCB as an attractive target for allogeneic cellular therapeutic options in tissue engineering.

A combination of catalase and trehalose as additives to conventional freezing medium results in improved cryoprotection of human hematopoietic cells with reference to in vitro migration and adhesion properties

BACKGROUND

Cryopreservation of hematopoietic cells from cord blood is an essential component in unrelated transplant settings. Cell damage during freezing is caused by multiple factors, of which membrane damage and oxygen free radical generation are two major factors. It was reported earlier that a combination of catalase and trehalose as additives in freezing medium affords better cryoprotection in terms of long-term culture assays.

STUDY DESIGN AND METHODS

Mononuclear and CD34+ cells isolated from cord blood were used as a source of hematopoietic cells. KG1a cell line was used as a model system in adhesion assays. The cells were frozen in a programmable freezer and stored at -196 degrees C. Various homing-related assays were carried out on the frozen cells.

RESULTS

Herein it is reported that these two additives afford better preservation of adhesion- and migration-related properties of the frozen cells. The test cells frozen with additives resulted in improved migration toward stromal-derived factor-1alpha and showed higher expression of its receptor CXCR4. Colony-forming unit assay of migrated test cells showed that these cells are early progenitors having capacity to give rise to all types of myeloid colonies. Test cells also show increased expression of FLT3R and improved responsiveness to FLT3 ligand, the homing-related cytokine. Adhesion to stroma and extracellular matrix was better in test cells as compared to control cells.

CONCLUSION

The present data provide evidence that addition of catalase and trehalose to the conventional freezing medium preserves migration- and adhesion-related properties of the hematopoietic graft.

A pilot study of tacrolimus and mycophenolate mofetil graft-versus-host disease prophylaxis in childhood and adolescent allogeneic stem cell transplant recipients

Tacrolimus (FK506)/mycophenolate mofetil (MMF) has been demonstrated to be an effective salvage therapy for steroid-resistant chronic graft-versus-host disease (GVHD), but its effectiveness as prophylaxis for acute GVHD (aGVHD) is unknown. We investigated the safety and efficacy of FK506/MMF in preventing aGVHD and sparing the use of methotrexate and methylprednisolone in childhood and adolescent allogeneic stem cell transplant (AlloSCT) recipients. Thirty-four childhood and adolescent patients (median age, 7 years; range, 0.5-21 years; 24 males and 10 females) undergoing 37 AlloSCTs for malignant (n = 22) and nonmalignant (n = 12) disorders received FK506 (0.03 mg/kg/d by continuous intravenous infusion) and MMF (15 mg/kg per dose orally or intravenously twice daily). Stem cell sources included 22 umbilical cord blood donors (21 unrelated and 1 related), 6 related bone marrow donors, and 9 related peripheral blood donors. Malignant diagnoses included 7 acute lymphoblastic leukemias, 3 acute myeloid leukemias, 1 acute promyelocytic leukemia, 2 non-Hodgkin lymphomas, 4 Hodgkin diseases, 3 chronic myeloid leukemias, and 2 neuroblastomas; nonmalignant diagnoses included 2 beta-thalassemias, 1 sickle cell disease, 4 aplastic anemias, 1 Wiskott-Aldrich syndrome, 1 Hurler syndrome, 2 hemophagocytic lymphohistiocytoses, and 1 myelodysplastic syndrome. The probability of developing grade > or =II aGVHD was 45.4% +/- 9.7% (7 related bone marrow/related peripheral blood; 5 umbilical cord blood), and for chronic GVHD it was 38.1% +/- 19.7%. FK506/MMF was well tolerated. Three patients had grade III to IV neurotoxicity (disorientation and leukoencephalopathy); 4 patients developed grade III to IV nephrotoxicity (all received concomitant nephrotoxins). Patients who achieved target mycophenolic acid levels (1.0-3.5 microg/mL) before day +30 had a significantly reduced incidence of developing grade >/=II aGVHD (16.7% +/- 15.2% versus 100%; P <.02). These results suggest that FK506/MMF is well tolerated and may be a safe and effective methotrexate- and methylprednisolone-sparing alternative GVHD prophylaxis regimen after AlloSCT. Further pharmacokinetic and pharmacodynamic studies are ongoing in pediatric and adolescent AlloSCT recipients to define optimal MMF dosing.

Stem cell factor improves SCID-repopulating activity of human umbilical cord blood-derived hematopoietic stem/progenitor cells in xenotransplanted NOD/SCID mouse model

Poor in vivo homing capacity of hematopoietic stem/progenitor cells (HS/PCs) from umbilical cord blood (UCB) can be reversed by short-term ex vivo manipulation with recombinant human stem cell factor (rHuSCF). This study was designed to evaluate the effect of ex vivo manipulation of UCB-derived HS/PCs with rHuSCF on human cell engraftment rates in xenotransplanted NOD/SCID mouse model. The human cell engraftment rates in xenotransplanted primary and secondary NOD/SCID mice were characterized using four-color flow cytometric analysis and progenitor assay. Grafts of rHuSCF-treated UCB CD34(+) cells resulted in significantly higher levels of human cell engraftment than that of nontreated ones in both xenotransplanted primary and secondary NOD/SCID recipients. Fresh UCB CD34(+) cells did not express either of the matrix metalloproteinase (MMP) family members MMP-2 or MMP-9. rHuSCF-treated UCB CD34(+) cells expressed significant levels of MMP-2 and MMP-9. Pretreatment of UCB CD34(+) cells with the specific MMP inhibitor completely blocked human cell engraftment in xenotransplanted NOD/SCID recipients. Our results indicate that ex vivo manipulation of human HS/PCs with rHuSCF might provide an optimal approach to develop more effective stem cell-based therapies in situations where engraftment is delayed due to limiting HS/PCs number, for example, UCB transplantation.

Effect of cryopreservation on the immunogenicity of umbilical cord blood cells

Cryopreservation is the accepted method for long-term storage of cord blood (CB) cells. We evaluated the effects of using different cooling rates (1, 5, 7.5 and 10 degrees C/min) on CB cell allostimulatory and alloproliferative function, antigen expression and clonogenic potential. Significant decreases (P<0.001-0.003) in viable cell recovery observed between fresh CB cells and CB cells cryopreserved at each cooling rate tested. Reductions in clonogenic potential of CB cells cryopreserved at cooling rates of 1, 5, 7.5 and 10 degrees C/min were 44%, 76%, 88% and 93% respectively, compared to fresh controls. FACS analysis indicated no changes in percentages CD34+ cells or lymphocytes. Two sets of mixed lymphocyte reactions were carried out for each CB sample. It was observed that allostimulatory and alloproliferative function varied following cryopreservation at different cooling rates (1 and 5 degrees C/min). Interestingly, there was a significant decrease (P<0.001-0.04) in the alloproliferative function of six of the seven CB samples following cryopreservation using a cooling rate of 5 degrees C/min. Cooling rates between 1 and 5 degrees C/min may provide immunomodulation of CB with maintenance of haematopoietic progenitor cells function.

Endothelial cells from hematopoietic stem cells are functionally different from those of human umbilical vein

Hematopoietic stem cells have a remarkable plastic capacity, which allows them to differentiate into various cells, such as immune cells, nervous cells, muscle cells, bone and cartilaginous cells. The aim of this study was to show the capacity of stem cells to differentiate into endothelial cells, in culture, after addition of endothelial cells growth supplement (ECGS). We also compared the behavior of these cells with that of endothelial cells obtained from human umbilical vein (HUVEC). CD34+ cells obtained by immunomagnetic separation from human umbilical cord and placental blood were used. After 12-15 days of culture in a medium containing ECGS, the cells showed morphological changes characteristic to endothelial cells and immunocytochemical analysis revealed the presence of CD31 surface antigen and von Willebrand factor. The flow-cytometric analysis of endothelial cells adhesion molecules (ECAM) showed that endothelial cells derived from CD34+ cells expressed CD54/ICAM-1 9.65+/-0.2% and CD106/VCAM 7.73+/-0.3%, values similar to those expressed by HUVECs. After TNF incubation, ECAM expression increased only in HUVECs. These data demonstrate that a fraction of circulating CD34+ cells may develop some endothelial cell characteristics when cultured with ECGS, but they are functionally different from HUVECs.

Ex vivo manipulation of umbilical cord blood-derived hematopoietic stem/progenitor cells with recombinant human stem cell factor can up-regulate levels of homing-essential molecules to increase their transmigratory potential

OBJECTIVE

The cause of delayed hematopoietic reconstitution after umbilical cord blood transplantation (UCBT) remains controversial. We hypothesized that hematopoietic stem/progenitor cells (HS/PCs) from UCB have some defects of the homing-related molecules responsible for their slow engraftment.

MATERIALS AND METHODS

A homing-related molecule repertoire expressed on HS/PCs from fresh and cryopreserved UCB, mobilized peripheral blood (mPB), and bone marrow (BM) were compared using sensitive, four-color fluorescence-activated cell sorting analysis. Purified CD34+ cells were subjected to ex vivo transmigration through double-coated transwell filter inserts, and an in vivo homing assay was performed in xenotransplanted NOD/SCID mice.

RESULTS

UCB-derived CD34(bright) cells expressed significantly lower levels of CD49e, CD49f, and CXCR-4 than their mPB and BM counterparts. CD34+ cells from UCB (and BM) exhibited significantly lower ex vivo transmigration than those from mPB, which were largely blocked by neutralizing antibodies to CD49e or CD49f. Recombinant human tumor necrosis factor-alpha treatment enhanced ex vivo transmigration of CD34+ cells from UCB and BM by inducing expression of the matrix metalloproteinases MMP-2/MMP-9. Short-term treatment of UCB-derived CD34+ cells with rHu-stem cell factor (rHuSCF) up-regulated levels of the homing-related molecules with their increased ex vivo transmigratory and in vivo homing potential.

CONCLUSION

Our results indicate that disadvantageous transmigratory behavior of HS/PCs from UCB, which might partly explain the delayed reconstitution after UCBT, can be reversed by ex vivo manipulation with rHuSCF.

Gene delivery using human cord blood-derived CD34+cells into inflamed glomeruli in NOD/SCID mice

BACKGROUND

Bone marrow reconstitution using genetically-modified hematopoietic stem cells has been reported to confer resistance to inflammation and prevent renal injury in glomerulonephritis. Although this strategy has potentials for clinical use, taking hematopoietic stem cells from bone marrow is highly stressful for patients. In this regard, umbilical cord blood may be a useful alternative and, therefore, we focused on their suitability as a source of hematopoietic stem cells for transplantation-based therapy for glomerulonephritis.

METHODS

CD34+ cells were obtained from human umbilical cord blood, retrovirally transduced with human beta-glucuronidase (HBG) gene, and transplanted into nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mice. After confirming the successful chimerism, these mice were treated with lipopolysaccharide (LPS), and local HBG expression in glomeruli was examined using immunohistochemical analysis, HBG bioassay, and Western blot analysis.

RESULTS

Clonogenic assay showed that 88.4 +/- 5.9% burst-forming unit-erythroid (BFU-E), 79.7 +/- 11.4% in colony-forming unit-macrophage (CFU-M), and 81.1 +/- 14.1% in colony-forming unit-granulocyte (CFU-G), respectively, possessed the transgene after transfection, suggesting that precommited cells were susceptible to retroviral infection. Flow cytometric analysis revealed that 24.1 +/- 14.5% of bone marrow cells in these chimera mice expressed human lymphocyte antigen (HLA) 8 weeks after transplantation. Also, clonogenic assay showed that a sustained engraftment of human hematopoietic cells expressed HBG. CD14-positive cells were recruited into the glomeruli upon LPS treatment and they secreted bioactive HBG, suggesting that cord blood-derived CD34+cells may differentiate into monocyte lineage while maintaining the expression of the transgene.

CONCLUSION

These data indicate that umbilical cord blood cells can be utilized as a source of hematopoietic stem cells for the transplantation-based therapy of glomerulonephritis.

Hematopoietic recovery after unrelated umbilical cord-blood allogeneic transplantation in adults treated with in vivo stem cell factor (R-MetHuSCF) and filgrastim administration

Transplantation with unrelated umbilical cord blood (UCB) is marked by delayed hematologic recovery. This report summarizes two adults with chronic myelogenous leukemia (CML), who received myeloablative conditioning followed by infusion of a non-expanded single UCB graft. These CML patients were enrolled in a clinical trial incorporating concomitant in vivo administration of stem cell factor (R-MetHuSCF) and filgrastim from day of UCB infusion until attained hematopoietic recovery. Each patient engrafted fully with donor UCB, with days to absolute neutrophil count (ANC) >500/microl being 13 and 29 days, respectively. Both patients remain in cytogenetic remission at 28 months follow-up. 'In vivo UCB expansion' with administration of concomitant R-MetHuSCF and filgrastim may facilitate prompt hematologic engraftment.

28. Embryonic and adult stem cell therapy

Stem cells are characterized by the ability to remain undifferentiated and to self-renew. Embryonic stem cells derived from blastocysts are pluripotent (able to differentiate into many cell types). Adult stem cells, which were traditionally thought to be monopotent multipotent, or tissue restricted, have recently also been shown to have pluripotent properties. Adult bone marrow stem cells have been shown to be capable of differentiating into skeletal muscle, brain microglia and astroglia, and hepatocytes. Stem cell lines derived from both embryonic stem and embryonic germ cells (from the embryonic gonadal ridge) are pluripotent and capable of self-renewal for long periods. Therefore embryonic stem and germ cells have been widely investigated for their potential to cure diseases by repairing or replacing damaged cells and tissues. Studies in animal models have shown that transplantation of fetal, embryonic stem, or embryonic germ cells may be able to treat some chronic diseases. In this review, we highlight recent developments in the use of stem cells as therapeutic agents for three such diseases: Diabetes, Parkinson disease, and congestive heart failure. We also discuss the potential use of stem cells as gene therapy delivery cells and the scientific and ethical issues that arise with the use of human stem cells.

Assessment of cell viability and apoptosis in human umbilical cord blood following storage

There is increasing use of human umbilical cord blood (UCB) stem cells for unrelated donor transplantation. Successful engraftment depends in large measure on the dose and quality of cells in the UCB unit. In the present study, we attempted to identify a simple and rapid technique for assessing the quality and recovery of UCB cells following laboratory manipulation. Mononuclear cells (MNC) from fresh (<48 h old) and thawed UCB units were stained with 7-amino-actinomycin D (7-AAD), revealing 2-3% dead cells. The frequencies of apoptotic cells in fresh and thawed sample were similar. However, UCB held for 72 h showed higher levels of cell deterioration. Interestingly, staining with 7-AAD was more sensitive to cellular damage than was uptake of Trypan Blue. 7-AAD staining of MNC also correlated with retention of hematopoietic function (progenitor assays) such that 7-AAD staining frequencies <20% predicted maintenance of hematopoietic cells. Importantly, hematopoietic precursors were less susceptible to storage injury than were UCB MNC as a whole. MNC showed higher levels of 7-AAD staining and apoptosis than did CD34(+) cells. This observation was confirmed in studies of caspase-3 activation, where MNC consistently showed higher frequencies of activation than did CD34(+) cells, especially after overnight storage. Furthermore, antiapoptotic proteins Bcl-2 and Bcl-x were expressed more consistently in CD34(+) cells than in total MNC. In contrast, Bax levels increased with MNC apoptosis. In conclusion, the data suggest that 7-AAD staining of UCB MNC provides a rapid and simple technique for assessing the viability, recovery, and hematopoietic functionality of stored UCB.

Cobblestone area-forming cells, long-term culture-initiating cells and NOD/SCID repopulating cells in human neonatal blood: a comparison with umbilical cord blood

Our prior study demonstrated that neonatal blood (NB) contained hematopoietic stem and progenitor cells that declined rapidly after birth. To validate that NB is a source of functional stem cells, we characterized this population in terms of cobblestone area-forming cells (CAFC), long-term culture-initiating cells (LTC-IC) and NOD/SCID mouse repopulating cells (SRC) in NB and umbilical cord blood (CB). Our data demonstrated that the frequencies of CAFC (30.2 vs 37.1, P = 0.14) and LTC-IC (28.6 vs 31.0, P = 0.49) in 1 x 10(5) mononuclear cells (MNC) of NB and CB were similar, suggesting that these cells were preserved in the circulation of the neonates shortly after birth. Sublethally irradiated NOD/SCID mice were transplanted with CD34(+) cells enriched from thawed NB and CB. At 6 weeks post transplant, human (hu)CD45(+) cells were detected in the bone marrow (BM), spleen and peripheral blood (PB) of the mice as demonstrated by flow cytometric and DNA analysis. Levels of huCD45(+)cells and colony forming units (CFU) appeared to be dependent on the infusion cell dose and were higher in animals receiving CB cells when compared with those of the NB group. The transplanted cells were capable of differentiation into multi-lineage progenitor cells (CD34(+) cells and differential CFU), as well as mature myeloid (CD14(+), CD33(+)), B lymphoid (CD19(+)) and megakaryocytic (CD61(+)) cells in the recipients. NB cells, subjected to ex vivo culture in an optimized preclinical condition, were significantly expanded to early and committed progenitor cells. Expanded NB contained SRC at a reduced quantity but with high proportions of CD14(+) cells and CD33(+) cells. Our study confirms that NB contains pluripotent hematopoietic stem and progenitor cells capable of homing and engrafting the NOD/SCID mice.

Murine neonatal CD4+ lymph node cells are highly deficient in the development of antigen-specific Th1 function in adoptive adult hosts

It is well established that murine neonates are biased toward Th2 responses. Th2-dominant responses are observed following immunization with a variety of Ags, using different carrier/adjuvant systems, and are seen in both BALB/c and C57BL/6 mice. Therefore, Th2 skewing appears to be a universal phenomenon unique to the neonatal period. One important question about this phenomenon is whether these responses are due to T cell intrinsic properties or are regulated by the neonatal environment. Here we have addressed this issue by transferring neonatal or adult CD4(+) lymph node cells to adoptive adult recombinase-activating gene 2(-/-) hosts and studied the development of Th responses. Neonatal CD4(+) cells were highly deficient in the development of both primary and secondary Ag-specific Th1 responses. This did not appear to be due to anergy of a developed population, since exogenous IL-2 only marginally increased production of the Th1 cytokine IFN-gamma. This profound Th1 deficiency was observed despite similar proliferation by neonatal and adult cells within the recombinase-activating gene 2(-/-) hosts. Moreover, neonatal CD4(+) cells up-regulated activation markers in a manner similar to adult CD4(+) cells. Therefore, although their proliferation and phenotypic maturation proceeded normally, neonatal CD4(+) cells appeared to be intrinsically deficient in the functional maturation of Th1 lineage cells. These results offer a candidate explanation for the reduced graft-vs-host responses observed following transplantation of cord blood cells or murine neonatal lymphoid cells to allogeneic adult hosts.

New approaches to hematopoietic cell transplantation for hematological diseases in children

Hematopoietic cell transplantation (HCT) has been used for more 30 years for the treatment of selected malignant and nonmalignant diseases. Traditionally, HCT for hematological disorders has relied on myeloablative conditioning before HLA-identical sibling bone marrow transplantation to correct the underlying hematological defect. Most children with hematological diseases who are referred to HCT have features that portend significant morbidity and early mortality. Among SAA patients who have HLA-identical sibling donors, younger patients with profound pancytopenia might be considered early for HCT. For others who lack sibling donors, patients who receive HCT from alternate sources have generally failed one or more courses of intensive immunosuppressive therapy and remain transfusion-dependent, some with hemosiderosis, red cell alloimmunization, and platelet transfusion refractoriness [44,46,48]. Currently, HCT for SCD is generally restricted to those who have experienced a significant sickle-related complication such as stroke, recurrent acute chest syndrome, or recurrent painful episodes [7,13]. In contrast, most reserve HCT in thalassemia for younger, Lucarelli class I, good-risk patients who have HLA-identical sibling donors, and veer away from older, high-risk thalassemics for whom transplantation is a riskier clinical intervention. For groups such as young adults with thalassemia major, HCT might become more widely applicable if its toxicity was reduced. Several approaches undergoing development include reduced-intensity conditioning and attempts to prevent GVHD. New methods to reduce the intensity and toxicity of conditioning as well as to use highly purified stem cells with the reduction in graft versus host disease may allow for the use of matched unrelated donors or haploidentical donors. This would serve to provide potentially more children who could benefit from stem cell transplantation with donors. These advances will hopefully lead to benefits for the majority of children who lack HLA-identical donors.

Second transplantation with CD34+ blood cells from an HLA-mismatched related donor after engraftment failure of transplanted cord blood cells

Unrelated cord blood transplantation (CBT) has been worldwide for bone marrow reconstitution. CBT is associated with a high frequency of engraftment failure and rejection due to a small dose of graft cells. In cases of engraftment failure or rejection following unrelated CBT, retransplantation from the original donors is impossible. We report a successful transplantation with CD34+ blood cells selected from a 2-loci HLA-mismatched mother to a child with acute monocytic leukemia after engraftment failure of the primary CBT. Selected CD34+ blood cell transplantation is a useful approach for retransplantation in the setting of engraftment failure.

Transforming growth factor beta, pleiotropic regulator of hematopoietic stem cells: potential physiological and clinical relevance

Transforming growth factor beta (TGF-beta) is a pleiotropic regulator of all stages of hematopoieis. Depending on the differentiation stage of the target cell, the local environment, and the concentration of TGF-beta, TGF-beta can be proproliferative or antiproliferative, proapoptotic or antiapoptotic, and/or prodifferentiative or antidifferentiative. TGF-beta is the major regulator of stem cell quiescence and can act directly or indirectly through effects on the marrow microenvironment. In addition, paracrine and autocrine actions of TGF-beta have overlapping but distinct regulatory effects on hematopoietic stem/progenitor cells. Neutralization of autocrine TGF-beta has therapeutic potential.