The development of effective methods to cryopreserve precious cell types has had tremendous impact on regenerative and transfusion medicine. Hematopoietic stem cell (HSC) transplants from cryopreserved umbilical cord blood (UCB) have been used for regenerative medicine therapies to treat conditions including hematological cancers and immodeficiencies. Red blood cell (RBC) cryopreservation in blood banks extends RBC storage time from 42 days (for hypothermic storage) to 10 years and can overcome shortages in blood supplies from the high demand of RBC transfusions. Currently, the most commonly utilized cryoprotectants are 10% dimethyl sulfoxide (DMSO) for UCB and 40% glycerol for RBCs. DMSO is significantly toxic both to cells and patients upon its infusion. Glycerol must be removed to <1% post-thaw using complicated, time consuming and expensive deglycerolization procedures prior to transfusion to prevent intravascular hemolysis. Thus, there is an urgent need for improvements in cryopreservation processes to reduce/eliminate the use of DMSO and glycerol. Ice recrystallization during cryopreservation is a significant contributor to cellular injury and reduced cell viability. Compounds capable of inhibiting this process are thus highly desirable as novel cryoprotectants to mitigate this damage. The first compounds discovered that were ice recrystallization inhibitors were the biological antifreezes (BAs), consisting of antifreeze proteins and glycoproteins (AFPs and AFGPs). As such, BAs have been explored as potential cryoprotectants, however this has been met with limited success. The thermal hysteresis (TH)activity and ice binding capabilities associated with these compounds can facilitate cellular damage, especially at the temperatures associated with cryopreservation. Consequently, compounds that possess “custom-tailored” antifreeze activity, meaning they exhibit the potent ice recrystallization inhibition (IRI) activity without the ability to bind to ice or exhibit TH activity,are highly desirable for potential use in cryopreservation. This thesis focuses on the rational design of potent ice recrystallization inhibitors and on elucidating important key structural motifs that are essential for potent IRI activity. While particular emphasis in on the development of small molecule IRIs, exploration into structural features that influence the IRI of natural and synthetic BAs and BA analogues is also described as these are some of the most potent inhibitors known to date. Furthermore, this thesis also investigates the use of small molecule IRIs for the cryopreservation of various different cell types to ascertain their potential as novel cryoprotectants to improve upon current cryopreservation protocols, in particular those used for the long-term storage of blood and blood products. Through structure-function studies the influence of (glyco)peptide length, glycosylation and solution structure for the IRI activity of synthetic AFGPs and their analogues is described. This thesis also explores the relationship between IRI, TH and cryopreservation ability of natural AFGPs, AFPs and mutants of AFPs. While these results further demonstrated that BAs are ineffective as cryoprotectants, it revealed the potential influence of ice crystal shape and growth progression on cell survival during cryopreservation. One of the most significant results of this thesis is the discovery of alkyl- and phenolicglycosides as the first small molecule ice recrystallization inhibitors. Prior to this discovery, all reported small molecules exhibited only a weak to moderate ability to inhibit ice recrystallization. To understand how these novel small molecules inhibit this process, structure-function studies were conducted on highly IRI active molecules. These results indicated that key structural features, including the configuration of carbons bearing hydroxyl groups and the configuration of the anomeric center bearing the aglycone, are crucial for potent activity. Furthermore, studies on the phenolic-glycosides determined that the presence of specific substituents and their position on the aryl ring could result in potent activity. Moreover, these studies underscored the sensitivity of IRI activity to structural modifications as simply altering a single atom or functional group on this substituent could be detrimental for activity. Finally, various IRI active small molecules were explored for their cryopreservation potential with different cell types including a human liver cell line (HepG2), HSCs obtained from human UCB, and RBCs obtained from human peripheral blood. A number of phenolic-glycosides were found to be effective cryo-additives for RBC freezing with significantly reduced glycerol concentrations (less than 15%). This is highly significant as it could drastically decrease the deglycerolization processing times that are required when RBCs are cryopreserved with 40% glycerol. Furthermore, it demonstrates the potential for IRI active small molecules as novel cryoprotectants that can improve upon current cryopreservation protocols that are limited in terms of the commonly used cryoprotectants, DMSO and glycerol.

Diss. (sammanfattning) : Sveriges lantbruksuniv., 2007. / Härtill 5 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv. / Härtill 5 uppsatser.

Probiotics are live microorganisms which when administered in adequate amounts confer one or more health benefits on the host. Different processing conditions, the acidic condition of the stomach and exposure to hydrolytic enzymes affect the viability and efficacy of probiotic organisms. This study investigated the protective effects of two biopolymers poly-gamma-glutamic acid (γ-PGA) and bacterial cellulose (BC) on probiotics during freeze drying and during exposure to simulated intestinal juices and bile salts. The antibacterial property of Bifidobacterium strains was also investigated against four pathogenic bacteria. γ-PGA, a naturally occurring biopolymer was produced by two bacteria (Bacillus subtilis ATCC 15245 and B. licheniformis ATCC 9945a) in GS and E media, γ-PGA yields of about 14.11g/l were achieved in shake flasks and molecular weight of up to 1620 k Da was recorded, γ-PGA production was scaled up in a fermenter with B. subtilis using GS medium. BC, an edible biopolymer was produced by Gluconacetobacter xylinus ATCC 23770 in HS medium and a modified HS (MHS) medium. A yield of about 1.37g/l was recorded and BC production with MHS medium was used for probiotic application. B. longum NCIMB 8809 B. breve NCIMB 8807 and B. animalis NCIMB 702716 showed the best antimicrobial properties against the investigated pathogens. Survival of Bifidobacterium strains was improved when protected with powdered BC (PBC) although γ-PGA offered better protection than PBC. Viability of B. longum NCIMB 8809, B. breve NCIMB 8807 and B. animalis NCIMB 702716 in simulated gastric juice (SGJ) and simulated intestinal juice with bile salts was improved when protected with 5% γ-PGA and 5% γ-PGA+PBC with a reduction of < 1 Log CFU/ml while a reduction of ≤2 Log CFU/ml was recorded in PBC protected cells. Protecting Bifidobacterium strains with γ-PGA, PBC or a novel γ-PGA + PBC combination is a promising method to deliver probiotic bacteria to the target site in order to confer their health benefits on the host.

Made available in DSpace on 2015-03-26T13:55:07Z (GMT). No. of bitstreams: 1 texto completo.pdf: 256712 bytes, checksum: 96078d7a918b47a581d54f5c6c68b221 (MD5) Previous issue date: 2006-08-14 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The aim of this study was to evaluate the effect of different cooling rates, equilibration times and permeating cryoprotectants on motility characteristics and plasma membrane integrity of cryopreserved goat spermatozoa. Three experiments were designed. In the first one was evaluated the effect of different cooling methods on goat semen cryopreservation. A total of 20 ejaculates from Saanen (n = 2) and Alpine (n = 2) goats were frozen using a standard dry skim milk yolk diluent with 5% glycerol. Aliquots of the extended semen were then cooled using two different cooling methods (PR1; Becker or PR2; Fürst, 2002), before being frozen in liquid nitrogen. The semen was evaluated by total motility, vigor and the response to hypoosmotic solution test (HOST), live/dead stain and thermo-resistance test (TRT), before and after thaw. In this experiment the cooling method PR2 protected cell viability better them PR1 during the criopreservation process, reducing cold shock damage and improving the cryosurvival of goat spermatozoa. In the second experiment was evaluated the effect of different equilibration times on motility characteristics and plasma membrane integrity of cryopreserved goat spermatozoa. A total of 20 ejaculates from Saanen (n = 2) and Alpine (n = 2) goats were frozen using a standard dry skim milk yolk diluent with 5% glycerol. Aliquots of the extended semen were then cooled using the cooling methodology described by Fürst (2002) and remained at the temperature of 5-4 °C by a period of 15 minutes (TE1) or 75 minutes (TE2). The semen was evaluated by total motility, vigor and the response to hypoosmotic solution test (HOST), live/dead stain and thermoresistance test (TRT), before and after thaw. In this experiment the equilibration time of 75 minutes protected the cell viability better than the period of 15 minutes during the criopreservation process, improving the cryosurvival of goat spermatozoa. In the third experiment was evaluated the effect of the glycerol (G) and ethylene glycol (EG), on motility characteristics of cryopreserved goat spermatozoa by the in vitro semen analyses. A total of 20 ejaculates from Saanen (n = 2) and Alpine (n = 2) goats were frozen using a standard dry skim milk-yolk diluent with 5% glycerol. Aliquots of the extended semen were then cooled using the cooling methodology described by Fürst (2002). The semen was evaluated by total motility, vigor and the response to hypoosmotic solution test (HOST), live/dead stain and thermo-resistance test (TRT), before and after thaw. In this experiment EG promoted a better protection of the spermatic cell viability during the cryopreservation than the G. In conclusion the use of the cooling method PR2 associated with the one hour equilibration period and the ethylene glycol improved the motility characteristics and integrity of plasma membrane, increasing the number of viable goat spermatozoa after cryopreservation. / O objetivo deste estudo foi avaliar o efeito de diferentes protocolos de resfriamento, tempos de equilíbrio e crioprotetores permeáveis sobre as características de motilidade e integridade de membrana de espermatozóides caprinos criopreservados. Para tal, foram delineados três experimentos. No experimento 1, avaliou-se o efeito de diferentes protocolos de resfriamento sobre a criopreservação de sêmen caprino. Um total de 20 ejaculados de bodes das raças Saanen (n = 2) e Alpina (n = 2) foram congelados utilizandose um meio à base de leite desnatado-gema, acrescido de 5% de glicerol. Alíquotas do sêmen, então, diluído, foram resfriadas até 5 °C, utilizando dois protocolos de resfriamento diferentes (PR1; média de -0,12 °C/min e PR2; média de -0,4 °C/min), antes de serem congeladas em nitrogênio liquido. O sêmen foi avaliado quanto à sua motilidade espermática progressiva, vigor, taxa de recuperação da motilidade, resposta ao teste hiposmótico (HOST) e coloração. Nesse experimento, a curva de resfriamento PR2 promoveu uma melhor proteção aos efeitos causados pelo choque térmico durante a criopreservação do sêmen caprino, que a curva PR1. No experimento 2, avaliou-se o efeito de dois períodos de equilíbrio sobre as características de motilidade e integridade de membrana de espermatozóides caprinos criopreservados. Um total de 20 ejaculados de animais da raça Saanen (n = 2) e Alpina (n = 2) foram congelados utilizando-se um meio à base de leite desnatado-gema, acrescido de 5% de glicerol. Alíquotas do sêmen diluído foram, então, resfriadas segundo Fürst (2002), e mantidas a temperatura de 5 °C, por um período de 15 minutos (TE1) ou 75 minutos (TE2) antes de serem congeladas em nitrogênio liquido. O sêmen foi avaliado quanto à sua motilidade espermática progressiva, vigor, resposta ao teste hiposmótico (HOST), ao teste supravital e ao teste de termorresistência (TTR), antes e após o congelamento. Nesse experimento, o tempo de equilíbrio de 75 minutos promoveu uma melhor criopreservação do sêmen caprino que o tempo de equilíbrio curto, de 15 minutos. No experimento 3, avaliou-se o efeito do glicerol e etileno glicol sobre a criopreservação de sêmen caprino, por meio de análises in vitro do sêmen. Um total de 20 ejaculados de animais da raça Saanen (n = 2) e Alpina (n = 2) foram congelados utilizando-se um meio à base de leite desnatado-gema, acrescido de 5% de glicerol. Alíquotas do sêmen diluído foram, então, resfriadas, utilizando-se a metodologia descrita por Fürst (2002). O sêmen foi avaliado quanto à sua motilidade espermática progressiva, vigor, resposta ao teste hiposmótico (HOST), ao teste supravital e ao teste de termorresistência (TTR), antes e após o congelamento. Nesse experimento, o uso do EG como crioprotetor permeável promoveu uma melhor proteção à viabilidade da célula espermática, durante o processo de criopreservação, que o glicerol. Em conclusão, o uso do protocolo de resfriamento 2, associado a um período de equilíbrio de 1 hora e ao uso do etileno glycol, promoveu uma melhor proteção das características de motilidade e integridade de membrana, aumentando a viabilidade dos espermatozóides caprinos congelados.

Made available in DSpace on 2016-12-08T16:24:10Z (GMT). No. of bitstreams: 1 PGCA12MA088.pdf: 670172 bytes, checksum: 978ec4d11d867f3e2959dae1534f76a9 (MD5) Previous issue date: 2012-02-24 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The viability evaluation of animal cells subjected to different cryopreservation strategies is important for studies in cell culture, application in animal cloning and the establishment and maintenance of gene banks. The aim of this study is optimize a method for cryopreservation of bovine somatic cells in different containers using different cryoprotectants. For this purpose, three experiments were conducted using bovine skin fibroblast cells obtained by ear biopsy explantation by ear biopsy of a female Flemish breed. In the first experiment the cells were cryopreserved in cryotubes at fixed concentration of 1x106 cells/mL and in three freezing culture medium (1) culture medium +10% DMSO, (2) culture medium + 10% propylene glycol, (3) culture medium + 10% ethylene glycol. In the second experiment the freezing was performed with the same solutions used in experiment 1, however, the cells were cryopreserved in 0.25 mL and 0.5 mL straws. In the third experiment cells in different concentrations, (0.33x106 cells/mL, 1x106 cells/mL, 3x106 cells/mL and 5x106 cells/mL) were cryopreserved in 0.5 mL straws with culture medium + 10% propylene glycol. In all experiments, the cells were thawed in waterbath at 37 oC for evaluation of cell survival by trypan blue method and by the cell growth curve after 72 h in culture, moreover, in the first experiment was carried out the population doubling time test (PDT). The data were analyzed by analysis of variance with pairwise comparisons between groups by the Tukey test, with significance level of 5%. In first experiment there was no significant difference between groups using different cryoprotectants and the time of cell division, estimated by PDT, ranged from 15.9 to 16.5 hours.In the second experiment no significant difference in the survival rate between groups was observed, regardless of the cryoprotectant used, and considering the 0.25 and 0.5 mL straws. In the growth curve, the survival performance of cells cryopreserved in 0.25 ml straws was statistically inferior to that frozen in 0.5 mL straws and cryovials. In this experiment all groups had significantly lower survival results campared to the control group. In the third experiment, the cell concentrations that presented a better survival rate after thawing were 0.33x106cells/ mL and 1x106 cells /mL. Based on the results obtained it follows that straws can be used for freezing cells and the straws of 0.5 mL showed results consistent with those obtained by cryotubes. Likewise the use of PG can be a viable alternative for the freezing somatic cells / A avaliação da viabilidade de células animais submetidas à criopreservação é importante para estudos em cultivo celular, aplicação em clonagem animal e para o estabelecimento e manutenção de bancos genéticos. O objetivo do trabalho é otimizar uma metodologia de criopreservação de células somáticas bovinas utilizando diferentes recipientes e crioprotetores. Para tanto, três experimentos foram conduzidos utilizando células fibroblásticas de origem cutânea foram obtidas por meio de biópsia auricular de uma fêmea da raça Flamenga. No primeiro experimento, as células foram criopreservadas em criotubos na concentração fixa de 1x106 células/mL em três soluções de congelamento (1) meio de cultivo +10% de DMSO; (2) meio de cultivo + 10% de Propileno glicol; (3) meio de cultivo + 10% de Etileno glicol. No segundo experimento, o congelamento foi realizado com as mesmas soluções crioprotetoras utilizadas no experimento um, porém as células foram criopreservadas em palhetas de 0,25 mL e 0,5 mL. No terceiro experimento, foram testadas diferentes concentrações celulares, (0,33x106 cel/mL, 1x106 cel/mL, 3x106 cel/mL e 5x106 cel/mL) que foram criopreservadas em palheta de 0,5 mL utilizando-se meio de cultivo + 10% propileno glicol. Em todos os experimentos, as células foram descongeladas em banho maria a 37 oC para avaliação da sobrevivência celular pelo método de azul de Tripan e avaliação da curva de crescimento celular após 72 h de cultivo, além disso, no primeiro experimento foi realizado o teste de population doubling time (PDT) e no segundo e terceiro experimento o grupo controle foi realizado com células criopreservadas em criotubo utilizando a solução de congelamento composta meio de cultivo +10% de DMSO. Os dados foram analisados através da análise de variância com comparações pareadas entre grupos pelo teste de Tukey, com nível de significância de 5%. No primeiro experimento, não houve diferença significativa entre os grupos utilizando diferentes crioprotetores e o tempo de divisão celular estimado pelo PDT variou de 15,9 a 16,5 horas. No segundo experimento, a taxa de sobrevivência pós descongelamento, considerando as palhetas de 0,25 e 0,5 mL, não apresentou diferença significativa entre os grupos, independente do crioprotetor utilizado. Já na curva de crescimento, a sobrevivência das células criopreservadas em palhetas de 0,25 mL apresentou um desempenho estatisticamente inferior às congeladas em palhetas de 0,5 mL e criotubos. Neste experimento todos os grupos apresentaram resultados de sobrevivência significativamente inferiores ao grupo controle. No terceiro experimento as concentrações celulares que apresentaram melhores resultados de sobrevivência após o descongelamento foram de 0,33x106 cel/mL e 1x106 cel/mL. Com base nos resultados obtidos conclui-se que é possível utilizar palhetas para o congelamento de células e que as palhetas de 0,5 mL apresentaram resultados compatíveis aos obtidos com criotubos. Da mesma forma o uso de PG pode ser uma alternativa viável para o congelamento de células somáticas

The first project in this work used classical molecular dynamics to study the ice recrystallization inhibition potential of a series of carbohydrates and alcochols, using the hydration index, partial molar volumes and isothermal compressibilities as parameters for measuring their cryogenic efficacy. Unfortunately, after 8 months of testing, this work demonstrates that the accuracy and precision of the density extracted from simulations is not sufficient in providing accurate partial molar volumes. As a result, this work clearly demonstrates that current classical molecular dynamics technology cannot probe the volumetric properties of interest with sufficient accuracy to aid in the research and development of novel cryoprotectants.The second project in this work used molecular dynamics simulations to evaluate the Gibbs free energy change of substituting CO2 in sI clathrate hydrates by N2,CH4, SO2 and H2S flue gas impurities under conditions proposed for CO2 capture (273 K, 10 bar). Our results demonstrate that CO2 substitutions by N2 in the small sI cages were thermodynamically favored. This substitution is problematic in terms of efficient CO2 capture, since the small cages make up 25% of the sI clathrate cages, therefore a significant amount of energy could be spent on removing N2 from the flue gas rather than CO2. The thermodynamics of CO2 substitution by CH4, SO2 and H2S in sI clathrate hydrates was also examined. The substitution of CO2 by these gases in both the small and large cages were determined to be favorable. This suggests that these gases may also disrupt the CO2 capture by sI clathrate hydrates if they are present in large concentrations in the combustion flue stream. Similar substitution thermodynamics at 200 K and 10 bar were also studied. With one exception, we found that the substitution free energies do not significantly change and do not alter the sign of thermodynamics. Thus, using a lower capture temperature does not significantly change the substitution free energies and their implications for CO2 capture by sI clathrate hydrates.

The development of effective methods to cryopreserve precious cell types has had tremendous impact on regenerative and transfusion medicine. Hematopoietic stem cell (HSC) transplants from cryopreserved umbilical cord blood (UCB) have been used for regenerative medicine therapies to treat conditions including hematological cancers and immodeficiencies. Red blood cell (RBC) cryopreservation in blood banks extends RBC storage time from 42 days (for hypothermic storage) to 10 years and can overcome shortages in blood supplies from the high demand of RBC transfusions. Currently, the most commonly utilized cryoprotectants are 10% dimethyl sulfoxide (DMSO) for UCB and 40% glycerol for RBCs. DMSO is significantly toxic both to cells and patients upon its infusion. Glycerol must be removed to <1% post-thaw using complicated, time consuming and expensive deglycerolization procedures prior to transfusion to prevent intravascular hemolysis. Thus, there is an urgent need for improvements in cryopreservation processes to reduce/eliminate the use of DMSO and glycerol. Ice recrystallization during cryopreservation is a significant contributor to cellular injury and reduced cell viability. Compounds capable of inhibiting this process are thus highly desirable as novel cryoprotectants to mitigate this damage. The first compounds discovered that were ice recrystallization inhibitors were the biological antifreezes (BAs), consisting of antifreeze proteins and glycoproteins (AFPs and AFGPs). As such, BAs have been explored as potential cryoprotectants, however this has been met with limited success. The thermal hysteresis (TH)activity and ice binding capabilities associated with these compounds can facilitate cellular damage, especially at the temperatures associated with cryopreservation. Consequently, compounds that possess “custom-tailored” antifreeze activity, meaning they exhibit the potent ice recrystallization inhibition (IRI) activity without the ability to bind to ice or exhibit TH activity,are highly desirable for potential use in cryopreservation. This thesis focuses on the rational design of potent ice recrystallization inhibitors and on elucidating important key structural motifs that are essential for potent IRI activity. While particular emphasis in on the development of small molecule IRIs, exploration into structural features that influence the IRI of natural and synthetic BAs and BA analogues is also described as these are some of the most potent inhibitors known to date. Furthermore, this thesis also investigates the use of small molecule IRIs for the cryopreservation of various different cell types to ascertain their potential as novel cryoprotectants to improve upon current cryopreservation protocols, in particular those used for the long-term storage of blood and blood products. Through structure-function studies the influence of (glyco)peptide length, glycosylation and solution structure for the IRI activity of synthetic AFGPs and their analogues is described. This thesis also explores the relationship between IRI, TH and cryopreservation ability of natural AFGPs, AFPs and mutants of AFPs. While these results further demonstrated that BAs are ineffective as cryoprotectants, it revealed the potential influence of ice crystal shape and growth progression on cell survival during cryopreservation. One of the most significant results of this thesis is the discovery of alkyl- and phenolicglycosides as the first small molecule ice recrystallization inhibitors. Prior to this discovery, all reported small molecules exhibited only a weak to moderate ability to inhibit ice recrystallization. To understand how these novel small molecules inhibit this process, structure-function studies were conducted on highly IRI active molecules. These results indicated that key structural features, including the configuration of carbons bearing hydroxyl groups and the configuration of the anomeric center bearing the aglycone, are crucial for potent activity. Furthermore, studies on the phenolic-glycosides determined that the presence of specific substituents and their position on the aryl ring could result in potent activity. Moreover, these studies underscored the sensitivity of IRI activity to structural modifications as simply altering a single atom or functional group on this substituent could be detrimental for activity. Finally, various IRI active small molecules were explored for their cryopreservation potential with different cell types including a human liver cell line (HepG2), HSCs obtained from human UCB, and RBCs obtained from human peripheral blood. A number of phenolic-glycosides were found to be effective cryo-additives for RBC freezing with significantly reduced glycerol concentrations (less than 15%). This is highly significant as it could drastically decrease the deglycerolization processing times that are required when RBCs are cryopreserved with 40% glycerol. Furthermore, it demonstrates the potential for IRI active small molecules as novel cryoprotectants that can improve upon current cryopreservation protocols that are limited in terms of the commonly used cryoprotectants, DMSO and glycerol.

Cord blood (CB) has emerged as a significant source of hematopoietic stem cells (HSC) for transplantation. Large distances between collection and processing sites combined with staff availability can lead to long processing delays of CB unit (CBU). Standard agencies limit CBU storage at room temperature (RT) to a maximum of 48 hours from collection to freezing. Slow-engraftment and graft failure are major issues related to CB transplantation. I hypothesized that prolonged storage at RT reduces the engraftment activities of CBU due to the loss in HSC numbers. I set to test my hypothesis by performing serial and limiting-dilution transplantation assays in immunodeficient mice. My results showed that the engraftment activity of CBU was significantly perturbed by prolonged storage (>40 hours) at RT. In line with my hypothesis, the transplantation assays suggested that the engraftment deficit originates from loss in HSC numbers. My findings provide results for CB banks to make an informed decision on how long CBU can be stored at RT before processing. Conversely, CBU must be cryopreserved before use, and loss of function can occur due to osmotic shock and mechanical damage from uncontrolled ice-crystal growth (ice-recrystallization) during freezing and thawing. Current cyroprotectants like dimethyl-sulfoxide fail to inhibit ice-recrystallization. However, a novel class of small ice-recrystallization inhibitor (IRI) molecules (N-aryl-D-aldonamides) have been developed. I hypothesized that supplementation of cryopreservation solution with IRIs will improve the post-thaw viability and engraftment activity of CBU. Herein, I identified two IRIs (IRI 2 and IRI 6) that improved the post-thaw recovery of hematopoietic clonogenic and multipotent progenitors. Moreover, supplementation of CB graft with IRI 2 was beneficial to engraftment and had no negative impact on the differentiation and self-renewal activities of HSCs. Taken together, my results demonstrate for the first time that IRI may be beneficial to the engraftment activity of HSC graft and support further investigation.

No description available.