Marrow transplantation. Can cord blood be used?

Cellular Subsets of Maternal Microchimerism in Umbilical Cord Blood

Maternal microchimerism may arise in the offspring during pregnancy, and may be favorable or unfavorable. Additionally, maternal cells present in umbilical cord blood used for stem cell transplantation may affect the outcome after transplantation. The aim of this study was to evaluate the cellular subset and frequency of maternal cells in umbilical cord blood following vaginal deliveries and elective Cesarean sections where the umbilical cord clamping time was measured. A total of 44 healthy women with normal pregnancies were included in the study. Of these, 24 delivered vaginally and 20 by elective Cesarean sections. In the fresh umbilical cord blood, cellular subsets of CD3+ (T-cells), CD19+ (B-cells), CD33+ (myeloid cells), CD34+ (hematopoietic progenitor cells) and CD56+ (natural killer cells) cells were isolated and DNA extracted. A single-nucleotide polymorphism unique to the mother was identified and maternal microchimerism in the different cellular fractions was detected using quantitative real-time polymerase chain reaction with a sensitivity of 0.01%. Overall, 5 out of the 44 (11%) umbilical cord blood samples contained maternal microchimerism. The positive fractions were total DNA (whole blood, n = 3), CD34+ (n = 1), CD56+ (n = 1) and CD34+/CD56+ (n = 1). Overall, four of the five (80%) positive samples were from Cesarean sections and one was from a vaginal delivery. The conclusion from this study is that maternal microchimerism in umbilical cord blood is not a common phenomenon but includes both lymphoid and hematopoietic progenitor lineages.

Background and future considerations for human cord blood hematopoietic cell transplantation, including economic concerns

Cord blood (CB) has been used since 1988 as a source of hematopoietic stem cells (HSCs) and progenitor cells for hematopoietic cell transplantation (HCT) to treat patients with malignant and nonmalignant disorders. CB has both advantages and disadvantages when compared with other tissue sources of HSCs such as bone marrow and mobilized peripheral blood, which are also being used in the setting of HCT. This short review focuses on some historical information, as well as current efforts that are being assessed to enhance the efficacy of CB HCT. Also of importance are the costs of CB, and the feasibility and economics of using such to be identified, and newly confirmed improvements worldwide for the greatest number of patients. In this context, simple methods that would not necessarily entail the need for selected cell-processing facilities to ex vivo expand or improve the CB graft's functional activity may be of interest, with one such possibility being the use of an orally active inhibitor of the enzyme dipeptidylpeptidase 4, alone or in combination with other new and innovative approaches for improving HSC engraftment and in vivo repopulating capability of CB.

Validation of cord blood split products prepared by an automated method

OBJECTIVES

In this study, we studied whether the contents of the two compartments of automatically processed cord blood (CB) units are comparable with respect to cell counts and viability and therefore suitable for clinical therapy.

BACKGROUND

CB-derived stem cells are increasingly used for allogeneic transplantation. Many centres prepare the transplants by automated methods allowing to split the product into two portions.

METHODS

CB was collected at different sites in Germany and transported to a single centre for processing. Before and after cryopreservation laboratory analyses were performed to compare the quality of the two CB segments.

RESULTS

In total, 33 products were processed [mean collection volume: 18·6 ± 1·2 mL (range 15·2-20·2 mL) segment A; mean: 4·7 ± 0·3 mL (range 4·2-5·2 mL) segment B]. CD34+ cell counts, viability of CD34+ cells and many other haematological parameters showed a good comparibility between the two segments. However, lymphocyte counts and results of clonogenic assays were significantly different between the two segments of the split product.

CONCLUSION

We conclude that the preparation of the cord blood unit by the automated process results in a homogenous distribution of stem and progenitor cells. However, our findings show that the clonogenic capacity differs between the two segments.

Milestones in umbilical cord blood transplantation

Since the first human cord blood transplant, performed in 1988, cord blood banks have been established worldwide for collection and cryopreservation of cord blood for allogeneic hematopoietic stem cell transplant. Umbilical cord blood (UCB) has now become one of the most commonly used source of hematopoietic stem cells for allogeneic transplantation. Today a global network of cord blood banks and transplant centers has been established for a common inventory with an estimated 600,000 UCB have been banked and more than 20,000 UCB units distributed worldwide for adults and children with severe hematological diseases. Several studies have shown that the number of cells is the most important factor for engraftment while some degree of HLA mismatches is acceptable. The absence of ethical concern, and the unlimited supply of cells explain the increasing interest of using cord blood for developing regenerative medicine.

History of cord blood transplantation

Since the first human cord blood transplant, performed 20 years ago, cord blood banks have been established worldwide for the collection and cryopreservation of cord blood for allogeneic hematopoietic stem cell transplant. A global network of cord blood banks and transplant centers has been established for a common inventory and study of clinical outcomes. Results of unrelated allogeneic cord blood transplants in malignant and nonmalignant diseases, in adults and children, show that, compared with HLA-matched unrelated BM transplant, cord blood has several advantages, including prompt availability of the transplant, decrease of GVHD and better long-term immune recovery resulting in a similar long-term survival. Several studies have shown that the number of cells is the most important factor for engraftment, although some degree of HLA mismatches is acceptable. Developments are expected to facilitate engraftment, including ex vivo expansion of stem cells, intrabone injection of cord blood cells and double cord blood transplants. In addition to hematopoietic stem cells, cord blood and placenta contain a large number of nonhematopoietic stem cells. In the absence of ethical concern, the unlimited supply of cells explains the increasing interest of using cord blood for developing regenerative medicine.

Two-way trafficking of Annexin V positive cells between mother and fetus: determination of apoptosis at delivery

OBJECTIVES

The aim of this study was to quantitate apoptosis in maternal circulation and umbilical cord blood (UCB) at delivery. The proportion of fetal cells in maternal blood as well as that of maternal cells in UCB was also determined.

MATERIAL AND METHODS

Three milliliters of peripheral blood was collected from nine women during labor. Five women delivered males and four delivered females. Immediately after delivery, 3 mL UCB was collected. Ten microliters was used to quantitate apoptosis by the ethidium bromide assay (EthBr) and from the remaining blood, Annexin V positive cells were isolated by MACS.

RESULTS

The Median apoptosis rate in maternal samples was 25% (19-34) and in UCB 20% (16-28). Annexin V positive cells were present in all samples analyzed. As shown by Fluorescence in situ hybridization (FISH) in maternal samples, cells with an XY hybridization pattern were identified in cases with male newborns in a median concentration of 1.7% (1.6-2.1). On the corresponding UCB, a median of 1.2% (0.8-1.6) XX cells were detected.

CONCLUSION

The study demonstrates the existence of a bidirectional transfer of fetal and maternal cells under apoptosis across the placenta and provides useful information regarding use of UCB for transplantation.

History of the clinical use of umbilical cord blood hematopoietic cells

The first cord blood (CB) transplant was performed in 1988 in a patient with Fanconi anemia. The donor was his HLA-identical sister who was known by pre-natal diagnosis to be HLA identical and not affected by the Fanconi mutation. The CB was collected and cryopreserved at birth. The transplant was successful without GvHD and the patient is currently alive and free of disease more than 15 years after transplant, with full hematologic and immunologic donor reconstitution. At the time of the first transplant, little was known about the biologic properties of CB cells and it was thanks to the pioneering work of H. E. Broxmeyer and E. A. Boyse, who studied the progenitor cell content of CB, and of A. D. Auerbach, who realized the pre-natal diagnosis of Fanconi anemia, that this transplant was possible. Since this first transplant, many questions have been answered but others are still open for further research. For example: would a single CB unit contain enough stem cells to permanently engraft children and adults? Would maternal cell contamination in fetal blood engraft and give severe GvHD? What are the immunologic properties of CB cells? How does it interfere with GvHD, GvL and immune reconstitution? Is the immune immaturity of CB lymphocytes able to overcome the HLA barrier and authorize HLA-mismatched transplants? Is it possible to establish CB banks for unrelated and related transplants? What would be the criteria for collection, quality control and cryopreservation?

Implication of maternal-cell contamination in the clinical banking of umbilical cord blood

BACKGROUND

The increasing utilization of human UC blood (UCB) in transplantation has drawn attention to the need for rationalization of selection, collection, processing, testing, banking and release of UCB. However, the issue of maternal blood contamination has not been well addressed. There are concerns that maternal T cells might elicit GvHD post-UCB transplant.

METHODS

Maternal T cells in 58 male UCB allografts were enumerated using fluorescent in situ hybridization and flow cytometry. Obstetric factors, preceding labor, multi-parity and gestational age, were also analyzed.

RESULTS

Levels of maternal cells of 0.75-5.25% were found in 15.5% (9/58) UCB. There was no association of maternal-cell contamination with preceding labor [25% (2/8) with previous delivery versus 35.4% (17/48) first born, P = 0.702], nor any correlation with multi-parity [37.5% (3/8) para > or = 3 versus 16.7% (8/48) para < 3, P = 0.181]. Gestation age of newborns also exhibited no association with maternal-cell contamination (39.47 weeks in newborn UCB with maternal cells, versus 39.58 weeks without: P = 0.674). The extrapolated maternal T cells/kg in nine UCB transplants were 1.05 x 10(5) +/- 1.12 x 10(5) (3.40 x 10(4) - 3.18 x 10(5)).

DISCUSSION

In relation to the arbitrary threshold of 1 x 10(5) T cells/kg in HLA-mismatched transplants utilizing T-cell depleted BM, 22.2% (2/9) of UCB transplants having maternal-cell contamination might be at risk of GvHD. Data support the need for testing for maternal blood in UCB, and evaluating the clinical relevance of GvHD in patients post-UCB transplant. The establishment of guidelines and standards for release of such UCB collections would be advisable in evidence-based UCB transplantation.

Long-term feto-maternal microchimerism: nature's hidden clue for alternative donor hematopoietic cell transplantation?

During pregnancy, fetal hematopoietic cells carrying paternal human leukocyte antigens (HLA) migrate into maternal circulation, and, vice versa, maternal nucleated cells can be detected in fetal organs and umbilical cord blood, indicating the presence of bidirectional cell traffic between mother and fetus. By taking advantage of fluorescence in-situ hybridization or polymerase chain reaction-based techniques, researchers recently found that postpartum persistence of such reciprocal chimerism was common among healthy individuals and may sometimes cause tissue chimerism. Although the biological significance of long-lasting feto-maternal microchimerism is unknown, a number of investigations have suggested its association with the development of "autoimmune" diseases such as systemic sclerosis. However, the very common presence of feto-maternal microchimerism among subjects without any autoimmune attack may allow us the more appealing hypothesis that it is an indicator for the acquired immunological hyporesponsiveness to noninherited maternal or fetal HLA antigens. An offspring's tolerance to noninherited maternal antigens has been clinically suggested by the retrospective analysis of renal transplantations or haploidentical hematopoietic stem cell transplantations, and whether postpartum mothers can tolerate paternally derived fetal antigens is an intriguing question. Although an exact linkage between microchimerism and transplantation tolerance is yet to be elucidated, long-term acceptance of a recipient's cell in the donor may have a favorable effect on preventing the development of severe graft-versus-host disease, and the donor cell microchimerism in the recipient might facilitate the graft acceptance. If this concept holds true, HLA-mismatched hematopoietic stem cell transplantation would be more feasible among haploidentical family members mutually linked with feto-maternal microchimerism. Further studies are warranted to investigate the potential role of feto-maternal microchimerism in human transplantation medicine.

Usefulness of cord-blood harvesting for autologous transfusion in surgical newborns with antenatal diagnosis of congenital anomalies

BACKGROUND/PURPOSE

The risks of homologous transfusion and the effectiveness of predeposit autologous transfusion have been described. The authors examined the clinical usefulness of cord-blood harvesting for autologous transfusion in newborns who had congenital anomalies antenatally diagnosed that would require surgical intervention at or near the time of delivery.

METHODS

Of 112 cases of antenatal diagnosis of congenital anomalies, 50 mothers gave informed consent and enrolled in this study. Cord-blood was withdrawn immediately after clamping of the umbilical cord and was used for autologous transfusion in newborns within the first 3 days postpartum.

RESULTS

A mean of 72 +/- 54 mL of cord-blood was harvested (27 +/- 18 mL/kg). While preserving cord-blood for 3 days at 4 degrees C, no signs of clot formation or hemolysis were observed. The harvested cord-blood included plasma-free Hb ranging from 1 to 68 (13 +/- 18) mg/dL and thrombin-antithrombin III complex ranging from 2 to 273 (18 +/- 50) ng/mL. Bacteriologic examination of the stored cord-blood showed negative cultures, except for samples from 3 newborns after vaginal delivery. A mean of 46 +/- 34 mL of cord-blood was used in 26 patients for autologous transfusion. No significant complications related to cord-blood transfusion were recognized clinically.

CONCLUSIONS

Autologous cord-blood transfusion has the potential to be a useful alternative to homologous transfusion in newborns requiring surgery. Adequate collection and storage techniques for cord-blood must be developed. J Pediatr Surg 36:851-854.

Placental blood for bone marrow replacement: the New York Blood Center's program and clinical results

BACKGROUND AND OBJECTIVES

Placental/umbilical cord blood (PCB) has been used for allogeneic bone marrow replacement since 1988. The Placental Blood Program of the New York Blood Center has developed techniques for collecting, testing, freezing and searching units on behalf of unrelated patients in need of hematopoietic stem cell replacement since 1993 and provided analysis of the outcomes of these transplants identified variables associated with clinical outcomes. In this review, after considering practical and conceptual aspects of the technology, we update information on the clinical outcomes of these transplants.

MATERIALS AND METHODS

All 861 patients transplanted through 1999 with PCB from our Program are included in this report. Two thirds were diagnosed with leukaemia or lymphoma, 25% with inherited conditions and 7% with acquired diseases. Outcome data were provided by the respective Transplant Center and analyses included both univariate and multivariate regression tests and actuarial (Kaplan-Meier) techniques.

RESULTS

Engraftment was achieved by over 90% of recipients (Kaplan-Meier estimate). Multivariate analysis confirmed the influence of cell dose, HLA matching, disease diagnosis and transplant center location (US vs. foreign). Patient age and HLA match grade independently affected the frequency and severity of acute graft vs. host disease. Leukaemic relapse was associated with the stage of disease at transplantation and the prior existence of acute graft vs. host disease. The probability of transplant-related events was independently associated with disease diagnosis, cell dose, number of HLA mismatches and transplant center, while the cell dose failed to associate significantly with the relative risk of reaching this endpoint in the subset of patients who achieved engraftment. Overall, event-free survival rates at one year post-transplant were 49 and 30%, respectively for genetic disease and haematologic malignancies and 35% for patients with acquired diseases, respectively.

CONCLUSIONS

These results confirm and extend earlier data, particularly establishing the significant association of transplant success with histocompatibility matching grades, and indicatng the urgency of improving the transplant match levels.

Cell dose and speed of engraftment in placental/umbilical cord blood transplantation: graft progenitor cell content is a better predictor than nucleated cell quantity

There is evidence that the total cellular content of placental cord blood (PCB) grafts is related to the speed of engraftment, though the total nucleated cell (TNC) dose is not a precise predictor of the time of neutrophil or platelet engraftment. It is important to understand the reasons for the quantitative association and to improve the criteria for selecting PCB grafts by using indices more precisely predictive of engraftment. The posttransplant course of 204 patients who received grafts evaluated for hematopoietic colony-forming cell (CFC) content among 562 patients reported previously were analyzed using univariate and multivariate life-table techniques to determine whether CFC doses predicted hematopoietic engraftment speed and risk for transplant-related events more accurately than the TNC dose. Actuarial times to neutrophil and platelet engraftment were shown to correlate with the cell dose, whether estimated as TNC or CFC per kilogram of recipient's weight. CFC association with the day of recovery of 500 neutrophils/μL, measured as the coefficient of correlation, was stronger than that of the TNC (R = −0.46 and −0.413, respectively). In multivariate tests of speed of platelet and neutrophil engraftment and of probability of posttransplantation events, the inclusion of CFC in the model displaced the significance of the high relative risks associated with TNC. The CFC content of PCB units is associated more rigorously with the major covariates of posttransplantation survival than is the TNC and is, therefore, a better index of the hematopoietic content of PCB grafts.

Cell dose and speed of engraftment in placental/umbilical cord blood transplantation: graft progenitor cell content is a better predictor than nucleated cell quantity

There is evidence that the total cellular content of placental cord blood (PCB) grafts is related to the speed of engraftment, though the total nucleated cell (TNC) dose is not a precise predictor of the time of neutrophil or platelet engraftment. It is important to understand the reasons for the quantitative association and to improve the criteria for selecting PCB grafts by using indices more precisely predictive of engraftment. The posttransplant course of 204 patients who received grafts evaluated for hematopoietic colony-forming cell (CFC) content among 562 patients reported previously were analyzed using univariate and multivariate life-table techniques to determine whether CFC doses predicted hematopoietic engraftment speed and risk for transplant-related events more accurately than the TNC dose. Actuarial times to neutrophil and platelet engraftment were shown to correlate with the cell dose, whether estimated as TNC or CFC per kilogram of recipient's weight. CFC association with the day of recovery of 500 neutrophils/μL, measured as the coefficient of correlation, was stronger than that of the TNC (R = −0.46 and −0.413, respectively). In multivariate tests of speed of platelet and neutrophil engraftment and of probability of posttransplantation events, the inclusion of CFC in the model displaced the significance of the high relative risks associated with TNC. The CFC content of PCB units is associated more rigorously with the major covariates of posttransplantation survival than is the TNC and is, therefore, a better index of the hematopoietic content of PCB grafts.

Quantitative Analysis of the Bidirectional Fetomaternal Transfer of Nucleated Cells and Plasma DNA

Background: Recently, much interest has been generated on the fetomaternal transfer of nucleated cells and plasma DNA. However, there has been no systematic quantitative comparison of these two directions and two modalities of trafficking within the same study population.

Methods: The fetus-to-mother transfer of nucleated cells and plasma DNA in pregnant women carrying male babies was studied using a real-time quantitative PCR assay for the SRY gene. For mother-to-fetus transfer, real-time quantitative PCR assays for the insertion/deletion polymorphisms involving the glutathione S-transferase M1 and angiotensin-converting enzyme genes were used.

Results: Of the 50 informative mother-baby pairs, maternal DNA was detected in the cellular fraction of umbilical cord blood in 24% of cases (12 of 50), at a median fractional concentration of 2.6 × 10−4 (interquartile range, 1.7 × 10−4 to 3.6 × 10−4). In the plasma fraction of cord blood, maternal DNA was detected in 30% (15 of 50) of cases at a median fractional concentration of 3 × 10−3 (interquartile range, 1 × 10−3 to 1.6 × 10−2). For the other direction of trafficking, fetus-to-mother transfer of nucleated cells was detected in 26% of cases (13 of 50) at a median fractional concentration of 3.2 × 10−4 (interquartile range, 0.6 × 10−4 to 7.6 × 10−4). In the plasma fraction, fetal DNA was detected in 100% of maternal plasma (50 of 50) at a median fractional concentration of 3 × 10−2 (interquartile range, 1.4 × 10−2 to 5.3 × 10−2).

Conclusions: This study indicated that significantly more fetal DNA is present in the plasma of pregnant women compared with DNA from the cellular fraction of maternal blood. In addition, maternal DNA was demonstrated in both the cellular and plasma fractions of cord blood after delivery. This study has therefore determined the fundamental quantitative values for the bidirectional fetomaternal cellular and plasma DNA traffic.

Potential for clinical use of viable pluripotent progenitor cells in blood bank stored human umbilical cord blood

There are indications that a close HLA match may not be necessary when human umbilical cord blood (HUCB) is used to effect a hematopoietic transplant. This was first suggested in 1972 and was further supported by the ability of HUCB to produce mouse survival following lethal irradiation. In China multiple units of HLA unmatched HUCB was utilized successfully in children to effect transplants. A recent publication indicated that newborn rodent blood cells can engraft in adult mice across the non-H-2 [corrected] antigens. Furthermore, there recently have been successful transplants with 3 antigens mismatched HUCB. In this study HUCB was stored in polyolefin blood bank bags at 4 degrees C. The storage was similar to that used in routine blood banking. Clonogenic assays were performed at Day 1 and 21 utilizing various growth factors. Replating efficiency was determined on colonies obtained from cord blood that was stored (non-frozen) for 21 days. The functional ability of day 21 old HUCB was determined by its ability to produce survival of lethally irradiated mice. It was found that approximately two-thirds (62.5%) of single primary blast cell colonies in day 21 stored HUCB could generate various types of secondary colonies. In some instances the secondary colonies were counted as high as 42 total mean colonies per single primary colony. These blast cell colonies (CFU-BL) were able to form single and multi lineage colonies composed of virtually every hematopoietic cell types. Animal survival studies were utilized in an effort to determine possible functional ability and were successful in producing fifty-day survival in 54% of lethally irradiated SJL/J mice and 100% ALB/C mice. This study holds the potential of making HUCB available for purposes of marrow transplantation to all who need it. It could further remove most of the moral and ethical issues related to HUCB, reduce to a fraction the cost in providing stem cells for marrow transplantation and potentially allow HUCB to be handled by existing blood banks.

Umbilical cord blood stem cells: application for the treatment of patients with hemoglobinopathies

Even though there is recognized morbidity and death associated with bone marrow transplantation, this procedure has been performed successfully in a substantial number of patients with hemoglobinopathies. However, finding a suitable related donor is often difficult and the morbidity associated with the use of unrelated donors is high. Several reports indicate that fewer than 30% of patients with thalassemia major and fewer than 20% of patients with sickle cell anemia have histocompatible siblings. Human umbilical cord blood (UCB) contains hematopoietic stem cells capable of reconstituting bone marrow. To date, approximately 200 transplantations have been performed with UCBs. Early results suggest that, even with substantial human leukocyte antigen (HLA) incompatibility, a decrease in the incidence of graft-versus-host disease occurs with cord blood. The extent to which HLA incompatibility can be tolerated when cord blood is used has not been determined. These results raise the possibility that UCB obtained from unrelated donors could be used for transplantation in patients with hemoglobinopathies. This review summarizes current data on UCB stem cells used for transplantation in hematologic diseases. The review contains a discussion of the potential uses of UCB for patients with hemoglobinopathies and the value of programs designed to collect UCB from newborn infants with hemoglobinopathies, from siblings of patients with hemoglobinopathies, and from groups of ethnic minorities similar to those in which hemoglobinopathies are found.

Allogeneic umbilical cord blood transplantation

Interest in umbilical cord blood as an alternate source of hematopoietic stem cells is growing rapidly. Umbilical cord blood offers the clinician a source of hematopoietic stem cells that is rarely contaminated by latent viruses and is readily available. Moreover, the collection of umbilical cord blood poses no risk to the donor; there is no need for general anesthesia or blood replacement, and the procedure causes no discomfort. Whether cord blood lymphocytes are as likely to cause GVHD as lymphocytes from older individuals is unknown. Current clinical experience would suggest that the incidence may be low. Few of the patients transplanted with umbilical cord blood thus far have developed clinically significant GVHD, including recipients of HLA-disparate grafts. These results and associated laboratory findings pose intriguing possibilities for the future of umbilical cord blood stem cells in the setting of unrelated transplantation. With the marked incidence of grade 2-4 acute GVHD that is currently observed after unrelated bone marrow transplantation, a reduction in incidence or severity would be a major advancement in this field. In the setting of autologous trans-plantation, there are other intriguing possibilities; for example, cord blood may be an optimal source of pluripotential stem cells for gene therapy. The large-scale collection and storage of cord blood stem cells has become a reality. Pilot programs for the banking of unrelated umbilical cord blood have already begun in the United States and Europe. Not only is there the potential for reducing the time from search initiation to the time of donor stem cell acquisition but also there is the potential for reducing the risks associated with unrelated bone marrow transplantation. There is also the hope of remedying the shortage of donors from ethnic and racial backgrounds that are currently underrepresented in most unrelated donor programs. Even with the creation of such banks, it should not be forgotten that the collection of umbilical cord bloods should at least be considered when a child with leukemia, lymphoma, neuroblastoma, marrow failure syndrome, immunodeficiency state, or inborn error of metabolism has a mother who is pregnant. The clinical results to date in small recipients would suggest that it is at least as good as bone marrow; but additional patients and more time will be needed to finalize this conclusion.

Hematopoietic transplant potential of unrelated cord blood: critical issues

To date, hematopoietic stem and progenitor cells from human umbilical cord blood (CB) have been employed in approximately 90 allogeneic (56 sibling and 34 unrelated) matched and mismatched transplantations worldwide with easy and successful restoration of hematopoiesis. Requests for stem cell preparations from CB will continue to increase. Thus, as a pilot study, the examination and standardization of unrelated cord blood-derived stem cell preparations and banking as well as their biologic characterization were initiated. Up to October 1995, a total of 574 samples [mean volume 79 +/- 26 ml, total nucleated cells (NC) 8.5 +/- 5 x 10(8), BFU-E 9.5 +/- 8.6 x 10(5), CFU-GM 5.7 +/- 6.3 x 10(5), CFU-GEMM 1.6 +/- 1.9 x 10(5)] from cord-derived or placental-derived residual blood have been defined by hematologic, immunologic, and microbiologic criteria. These CB samples were collected from the umbilical cord vein immediately after vaginal full-term delivery (n = 450) or cesarean section (n = 124) and stored frozen in liquid nitrogen. Seven percent of all samples collected could not be considered for potential transplants because of volumes < 40 ml. Only 5.0 ml of a CB sample is required for routine laboratory testing, consisting of HLA class I typing, HLA class II typing by sequence-specific oligonucleotide probes (PCR-SSOP), ABO typing, sterility control, assessment of progenitor and stem cells by colony-forming and LTC-IC assays, and CD34+ status. To assess the potential problem of contaminating maternal cells, a PCR was performed on 7 representative samples. During the initial 6 months of the unrelated CB collection program, a median bacterial contamination rate of 18% (20% skin flora species, 80% perineal flora species) was encountered, which has since been reduced to < 1% through practical experience. With regard to viral infections, maternal sera was tested for HBsAg (0.6% positive), anti-HCV (0%), anti-HAV (IgG 18%, IgM 0%), anti-HIV-1-2 (0%), anti-EBV (IgG 98%, IgM 0%), anti-HTLVI-II (0%), anti-CMV (IgG 43%, IgM 0.4%), toxoplasmosis (46%) and syphilis (0%). In addition, all cord blood samples were tested by PCR for CMV infection. With regard to its clinical relevance, it is important that only 0.3% of all the samples were positive for CMV by this sensitive method. This may represent a critical advantage of CB grafts over bone marrow (BM) since, in contrast, > 40% of the unrelated BM donors have been identified to be positive for CMV. An additional advantage of CB is that since 20% of CB samples were collected from ethnic minorities, it appears possible to balance common HLA types and uncommon HLA types represented in this group. In summary, with the extensive practical experience of the obstetric collection team as well as the stem cell-processing laboratory, it appears feasible to obtain a 90% yield of unrelated CB-derived stem cell preparations for banking, which clearly should meet the medical and regulatory qualification criteria required for clinical transplantation. To test the feasibility of hematopoietic transplant potential of unrelated CB for adult patients, ex vivo expansion of CD34+-enriched stem/progenitor cell populations isolated from fresh or frozen CB was attempted in the presence of rh-IL-3, rh-IL-6, rh-EPO, rh-GM-CSF, and rh-SCF with or without fit 3. At varying time points (days 0, 2, 4, 7, 14, 21), the contents of these cultures were analyzed for the numbers of cells, CFC (BFU-E, CFU-GM, CFU-GEMM), and LTC-IC. In this setting, the increase of cells was 200-fold, that of CFC 70-fold, and most importantly that of LTC-IC was 4.5-fold after 7 days in culture in the presence of flt3. In conclusion, LTC-IC derived from CB can be maintained and considerably expanded ex vivo from highly enriched CD34 + CB cell populations from fresh or frozen CB samples.

Density separation of umbilical cord blood and recovery of hemopoietic progenitor cells: implications for cord blood banking

Umbilical cord blood (CB) has been evaluated as a potential source of hematopoietic stem cells suitable for clinical use in the transplantation setting. Previous reports have documented a significant loss of progenitor cells by any manipulation other than cryopreservation. We have evaluated the feasibility of fractionating and cryopreserving CB samples with minimal loss of progenitor cells. We have compared various separation procedures based on different density gradients in the attempt to obtain the highest depletion of red blood cells (RBC) while maintaining the highest recovery of progenitor cells. We compared three different densities of Percoll (1.069 g/ml, 1.077 g/ml, 1.084 g/ml), sedimentation over poligeline (Emagel ) and sedimentation over poligeline followed by separation over Ficoll/Hypaque (F/H). Separated samples (n = 25) were analyzed for recovery of CD34+ cells and progenitor cells (CFU-GEMM, BFU-E, CFU-GM). Separation by sedimentation over poligeline followed by F/H allowed the highest depletion of RBC (hematocrit of the final cellular suspension 0.4 +/- 0.1%) while maintaining high recovery of CD34+ cells (85.3 +/- 5.6%) and total recovery for CFU-GEMM, BFU-E and CFU-GM. After cryopreservation, recovery of clonogenic progenitors was 82% for CFU-GEMM, 94% for BFU-E, 82% for CFU-GM and 90% for colony-forming units (CFUs) after five weeks of long-term culture (LTC). We further evaluated the effect of stem cell factor (SCF) on the in vitro growth of hemopoietic progenitors and on replating efficiency.(ABSTRACT TRUNCATED AT 250 WORDS)

Allogeneic sibling umbilical-cord-blood transplantation in children with malignant and non-malignant disease

Allogeneic bone marrow transplantation is limited by the availability of suitable marrow donors and risk of graft-versus-host disease (GVHD) and opportunistic infection. In an attempt to ameliorate these limitations, umbilical cord blood has been postulated as an alternative source of allogeneic haemopoietic stem cells for transplantation. From September, 1994, umbilical cord blood from sibling donors has been used to reconstitute haemapoiesis in 44 children with acquired or congenital lympho-haemapoietic disorders, neuroblastoma, or metabolic diseases. Patients who had HLA-identical and HLA-1 antigen disparate grafts, had a probability of engraftment at 50 days after transplantation of 85%. No patient had late graft failure. The probability of grade II-IV GVHD at 100 days was 3% and the probability of chronic GVHD at one year was 6%. With a median follow-up of 1.6 years, the probability of survival for recipients of HLA-identical or HLA-1 antigen disparate grafts is 72%. We conclude that umbilical cord blood is a sufficient source of transplantable haemopoietic stem cells for children with HLA-identical or HLA-1 antigen disparate sibling donors with very low risk of acute or extensive chronic GVHD. The feasibility of umbilical-cord-blood transplantation with HLA-2 and HLA-3 antigen disparate sibling donors remains to be determined.

Haemopoietic stem/progenitor cell transplant in Fanconi anaemia using HLA-matched sibling umbilical cord blood cells

There have only been a few reports documenting the use of umbilical cord blood as a source of stem cells for haemopoietic reconstitution. We report our experience with a child with Fanconi anaemia (FA) who underwent a stem cell transplant using umbilical cord blood cells from his HLA matched sibling. Although the engraftment was somewhat slow, it was complete and comparable to other transplants performed in FA patients using HLA matched sibling marrow. There was no graft-versus-host disease. The post-transplant period was uncomplicated and, at a follow-up of 36 months, this child is well with normal blood counts and immune function.

Placental blood-derived hematopoietic stem cells for unrelated bone marrow reconstitution

"Transplants" of placental blood from siblings have been successful in the reconstitution of ablated bone marrow. We are currently evaluating the feasibility of applying this source of hematopoietic stem cells in the case of unrelated recipients. Availability, ease and low cost of recovery, absence of risk to the donors, unbiased ethnic participation, and possibly advantageous immunological and infectious disease characteristics are evident advantages in comparison to registries of volunteer marrow donors. In this report we review selected aspects of the comparison and discuss selected areas of special interest to the practical application of this source of stem cells. We also present new data that reinforce earlier suggestions of a reduced capacity of allorecognition of placental blood lymphocytes, using as controls the lymphocytes of their respective HLA-identical siblings.

Simultaneous genotypic and immunophenotypic analysis of interphase cells for the detection of contaminating maternal cells in cord blood and their respective CFU-GM and BFU-E

Contamination of cord blood (CB) specimens by maternal blood provides a source of cells that may be capable of graft-versus-host reactivity. To confirm the genetic purity of collected CB samples (six samples, volume 110 +/- 21 ml, total nucleated cells 1.22 +/- 0.36 x 10(9)) the HLA-DR beta exon 2 for the noninherited material allele was examined by polymerase chain reaction amplification. No maternal cell contamination was detected in samples of 1 x 10(5) cells. In the case where the mother was homozygous for DR and DQ, the purity of the sample could not be tested by PCR and therefore in situ hybridization on interphase cells with a fluorescein labeled Y- and X-probe in male CB specimens was performed. This sensitive method also revealed no contamination of the CB by maternal white cells. In addition, picked CB-CFU-GM and BFU-E colonies (cultured in hu-SLF, GM-CSF, and Epo) were analyzed by simultaneous genotypic (for Y and X) and immunophenotypic analysis (monoclonal antibodies [MAbs] CD13, CD14, CD2, CD8, CD4, and glycophorin A). This approach permits simultaneous visualization of both the immunophenotype (MAbs, APAAP, red fluorescence) and the genotype (chromosomes, fluorescein isothiocyanate, green fluorescence) within the same cell. In contrast to PCR and restriction fragment length polymorphism, this method has the advantage that the donor-recipient origin of each lymphohematopoietic lineage (i.e., BFU-E, CFU-GM, T cells, B cells) can be determined in sex-mismatched transplantations. Thus confocal scanning laser microscopy is most suitable not only for the detection of contaminating maternal cells, but also for the detection of mixed hematopoietic chimerism after transplantation.

Phenotypic and functional immaturity of human umbilical cord blood T lymphocytes

Successful implementation of bone marrow transplantation for hematopoietic reconstitution is limited by the lack of suitably HLA-matched donors and by the occurrence of graft-versus-host disease that frequently accompanies this procedure. Recent clinical reports have implied that the use of umbilical cord blood as a source of transplantable stem cells may solve these problems. To date, definitive experiments have not been performed to assess the immunological potential of T cells found in umbilical cord blood, which could mediate graft-versus-host disease. In the present study we have observed that umbilical cord blood contains T lymphocytes that appear to be phenotypically immature. In addition, umbilical cord blood lymphocytes appeared to be functionally immature as shown by minimal responses to stimulation with interleukin 2, phytohemagglutinin, or alloantigens. Thus, umbilical cord blood may be more suitable for allogeneic transplantation than bone marrow in that these cord blood cells may not be as capable of mediating graft-versus-host disease.

Growth of human umbilical-cord blood in longterm haemopoietic cultures

Cryopreserved human umbilical-cord (HUC) blood is an alternative to bone marrow as a source of haemopoietic "stem" cells for HLA-identical transplantation of children with leukaemia or Fanconi's anaemia. We have studied the in-vitro growth potential of HUC blood in clonogenic assays and in longterm haemopoietic cultures. Clonogenic assays showed that HUC blood produced as many haemopoietic-cell colonies as normal adult bone marrow and a higher proportion of primitive-cell colonies. In longterm culture on preformed irradiated marrow stroma, both progenitor-cell production and lifespan of cultures were significantly greater in HUC blood than in normal bone marrow (p = 0.0007). Our findings indicate that the quality and quantity of HUC-blood-derived haemopoietic "stem" cells are better than those of normal bone marrow. Therefore, single HUC-blood donations are probably sufficient for adults requiring transplantation for leukaemia and other haemopoietic disorders. Banking of HLA-typed HUC blood to facilitate transplantation of patients who lack a family donor should be considered.

Human umbilical cord blood: a clinically useful source of transplantable hematopoietic stem/progenitor cells

This is a review and discussion of studies leading to the first use of human umbilical cord blood, material usually discarded, for the provision of stem/progenitor cells for clinical hematopoietic reconstitution. This prospect arose as a result of extensive studies of the harvesting and cryopreservation of cord blood and of its numerical content of progenitor cells demonstrable in vitro. A male patient with Fanconi anemia (FA) was conditioned with a modified regimen of cyclophosphamide and irradiation that accommodates the abnormally high sensitivity to these agents that is characteristic of FA. Cryopreserved cord blood had been retrieved at birth from a female sibling known from prenatal testing to be unaffected by FA and to be human leukocyte antigen (HLA)-compatible with the prospective sibling recipient. After conditioning and therapeutic infusion of thawed cord blood, successful hematopoietic reconstitution was indicated by the general health of the patient, who had previously required supportive transfusions, by satisfactory hematological criteria and by counts of hematopoietic progenitor cells of various types in the bone marrow. Complete engraftment of the myeloid system with donor cells was evident from cytogenetics, ABO typing, study of DNA polymorphisms, and normal cellular resistance to cytotoxic agents that reveal the fragility of FA cells; the blood contained a residuum of host lymphocytes exhibiting chromosomal damage, but the trend has been towards eliminating these damaged cells. This implies that cord blood from a single individual should provide sufficient reconstituting cells for effective hematopoietic repopulation of an autologous or an HLA-compatible allogeneic recipient.