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Credit: NHS
Investigators say they have identified a molecule that allows for robust ex vivo expansion of human cord blood (CB) cells.
CB cells expanded with this molecule, known as UM171, were capable of human hematopoietic reconstitution in NSG mice, an effect that lasted more than 6 months.
The researchers believe UM171 acts by enhancing the long-term-hematopoietic stem cell (LT-HSC) self-renewal machinery independently of AhR suppression.
Guy Sauvageau, MD, PhD, of the University of Montreal in Quebec, Canada, and his colleagues identified UM171 and described the discovery in Science.
The team first screened a library of 5280 low-molecular-weight compounds looking for those with the ability to expand human CD34+CD45RA- mobilized peripheral blood cells, which are enriched in LT-HSCs.
They got 7 hits, and only 2 of these—UM729 and UM118428—did not suppress the AhR pathway. The researchers selected UM729 for further characterization and optimization because it demonstrated superior activity in expanding CD34+CD45RA- cells.
The investigators analyzed more than 300 newly synthesized analogs of UM729 and identified one that was 10 to 20 times more potent than UM729. That compound was UM171.
UM171 could expand CD34+CD45RA- cells at concentrations of 17 nM to 19 nM. The highest expansion of multipotent progenitors and long-term culture-initiating cells occurred on day 12.
The effect of UM171 required its constant presence in the media, and the compound lacked direct mitogenic activity. UM171 did not affect the division rate of phenotypically primitive cell populations.
The researchers compared UM171 to SR1 (a compound known to promote self-renewal of HSCs) in fed-batch culture. They found that frequencies of CD34+ CB cells were similar in cultures containing SR1 and those containing UM171. But CD34+CD45RA- cells were more abundant with UM171 (P<0.005).
The team then evaluated LT-HSC populations. Twenty weeks after CD34+ CB cells were transplanted into mice, LT-HSC frequencies were similar in mice that received control and SR1-expanded cells. But LT-HSC frequencies were 13-fold higher in the mice that received UM171-expanded cells.
Next, the investigators assessed human hematopoietic reconstitution in NSG mice transplanted with fresh or expanded cells. They observed 2 patterns of reconstitution. One was from predominantly lymphomyeloid LT-HSCs that occurred with high cell doses in most conditions.
And the other was from LT-HSCs that display a lymphoid-deficient differentiation phenotype mostly observed with UM171 treatment, with or without SR1. However, UM171 did not negatively affect B lymphopoiesis or the frequency or number of lymphomyeloid LT-HSCs.
The impact of UM171 on LT-HSCs was preserved at 30 weeks post-transplant. And myeloid cell output was slightly augmented, a phenomenon that has been observed with normal, unexpanded cells.
The researchers also transplanted UM171-treated LT-HSC populations into secondary recipients. And they found the cells were still competent, but they had no advantage over unmanipulated CD34+ cells.
A clinical study of UM171 and a new type of bioreactor developed for stem cell culture is set to begin this December. The cells will be expanded at Maisonneuve-Rosemont Hospital, and grafts will be distributed to patients in Montreal, Quebec City, and Vancouver. The investigators expect tangible results will be available in December 2015. 
Credit: NHS
Investigators say they have identified a molecule that allows for robust ex vivo expansion of human cord blood (CB) cells.
CB cells expanded with this molecule, known as UM171, were capable of human hematopoietic reconstitution in NSG mice, an effect that lasted more than 6 months.
The researchers believe UM171 acts by enhancing the long-term-hematopoietic stem cell (LT-HSC) self-renewal machinery independently of AhR suppression.
Guy Sauvageau, MD, PhD, of the University of Montreal in Quebec, Canada, and his colleagues identified UM171 and described the discovery in Science.
The team first screened a library of 5280 low-molecular-weight compounds looking for those with the ability to expand human CD34+CD45RA- mobilized peripheral blood cells, which are enriched in LT-HSCs.
They got 7 hits, and only 2 of these—UM729 and UM118428—did not suppress the AhR pathway. The researchers selected UM729 for further characterization and optimization because it demonstrated superior activity in expanding CD34+CD45RA- cells.
The investigators analyzed more than 300 newly synthesized analogs of UM729 and identified one that was 10 to 20 times more potent than UM729. That compound was UM171.
UM171 could expand CD34+CD45RA- cells at concentrations of 17 nM to 19 nM. The highest expansion of multipotent progenitors and long-term culture-initiating cells occurred on day 12.
The effect of UM171 required its constant presence in the media, and the compound lacked direct mitogenic activity. UM171 did not affect the division rate of phenotypically primitive cell populations.
The researchers compared UM171 to SR1 (a compound known to promote self-renewal of HSCs) in fed-batch culture. They found that frequencies of CD34+ CB cells were similar in cultures containing SR1 and those containing UM171. But CD34+CD45RA- cells were more abundant with UM171 (P<0.005).
The team then evaluated LT-HSC populations. Twenty weeks after CD34+ CB cells were transplanted into mice, LT-HSC frequencies were similar in mice that received control and SR1-expanded cells. But LT-HSC frequencies were 13-fold higher in the mice that received UM171-expanded cells.
Next, the investigators assessed human hematopoietic reconstitution in NSG mice transplanted with fresh or expanded cells. They observed 2 patterns of reconstitution. One was from predominantly lymphomyeloid LT-HSCs that occurred with high cell doses in most conditions.
And the other was from LT-HSCs that display a lymphoid-deficient differentiation phenotype mostly observed with UM171 treatment, with or without SR1. However, UM171 did not negatively affect B lymphopoiesis or the frequency or number of lymphomyeloid LT-HSCs.
The impact of UM171 on LT-HSCs was preserved at 30 weeks post-transplant. And myeloid cell output was slightly augmented, a phenomenon that has been observed with normal, unexpanded cells.
The researchers also transplanted UM171-treated LT-HSC populations into secondary recipients. And they found the cells were still competent, but they had no advantage over unmanipulated CD34+ cells.
A clinical study of UM171 and a new type of bioreactor developed for stem cell culture is set to begin this December. The cells will be expanded at Maisonneuve-Rosemont Hospital, and grafts will be distributed to patients in Montreal, Quebec City, and Vancouver. The investigators expect tangible results will be available in December 2015.
Credit: NHS
Investigators say they have identified a molecule that allows for robust ex vivo expansion of human cord blood (CB) cells.
CB cells expanded with this molecule, known as UM171, were capable of human hematopoietic reconstitution in NSG mice, an effect that lasted more than 6 months.
The researchers believe UM171 acts by enhancing the long-term-hematopoietic stem cell (LT-HSC) self-renewal machinery independently of AhR suppression.
Guy Sauvageau, MD, PhD, of the University of Montreal in Quebec, Canada, and his colleagues identified UM171 and described the discovery in Science.
The team first screened a library of 5280 low-molecular-weight compounds looking for those with the ability to expand human CD34+CD45RA- mobilized peripheral blood cells, which are enriched in LT-HSCs.
They got 7 hits, and only 2 of these—UM729 and UM118428—did not suppress the AhR pathway. The researchers selected UM729 for further characterization and optimization because it demonstrated superior activity in expanding CD34+CD45RA- cells.
The investigators analyzed more than 300 newly synthesized analogs of UM729 and identified one that was 10 to 20 times more potent than UM729. That compound was UM171.
UM171 could expand CD34+CD45RA- cells at concentrations of 17 nM to 19 nM. The highest expansion of multipotent progenitors and long-term culture-initiating cells occurred on day 12.
The effect of UM171 required its constant presence in the media, and the compound lacked direct mitogenic activity. UM171 did not affect the division rate of phenotypically primitive cell populations.
The researchers compared UM171 to SR1 (a compound known to promote self-renewal of HSCs) in fed-batch culture. They found that frequencies of CD34+ CB cells were similar in cultures containing SR1 and those containing UM171. But CD34+CD45RA- cells were more abundant with UM171 (P<0.005).
The team then evaluated LT-HSC populations. Twenty weeks after CD34+ CB cells were transplanted into mice, LT-HSC frequencies were similar in mice that received control and SR1-expanded cells. But LT-HSC frequencies were 13-fold higher in the mice that received UM171-expanded cells.
Next, the investigators assessed human hematopoietic reconstitution in NSG mice transplanted with fresh or expanded cells. They observed 2 patterns of reconstitution. One was from predominantly lymphomyeloid LT-HSCs that occurred with high cell doses in most conditions.
And the other was from LT-HSCs that display a lymphoid-deficient differentiation phenotype mostly observed with UM171 treatment, with or without SR1. However, UM171 did not negatively affect B lymphopoiesis or the frequency or number of lymphomyeloid LT-HSCs.
The impact of UM171 on LT-HSCs was preserved at 30 weeks post-transplant. And myeloid cell output was slightly augmented, a phenomenon that has been observed with normal, unexpanded cells.
The researchers also transplanted UM171-treated LT-HSC populations into secondary recipients. And they found the cells were still competent, but they had no advantage over unmanipulated CD34+ cells.
A clinical study of UM171 and a new type of bioreactor developed for stem cell culture is set to begin this December. The cells will be expanded at Maisonneuve-Rosemont Hospital, and grafts will be distributed to patients in Montreal, Quebec City, and Vancouver. The investigators expect tangible results will be available in December 2015.