Skip to main content
eScholarship
Open Access Publications from the University of California

Scholarly Works (36 results)

  • Thesis
  • Peer Reviewed
UC San Francisco Electronic Theses and Dissertations (2024)

Genome editing is poised to revolutionize treatment of genetic diseases, but poor understanding and control of DNA repair outcomes hinders its therapeutic potential. DNA repair is especially understudied in nondividing cells like neurons, which must withstand decades of DNA damage without replicating. This lack of knowledge limits the efficiency and precision of genome editing in clinically relevant cells. To address this, we used induced pluripotent stem cells (iPSCs) and iPSC-derived neurons to examine how postmitotic human neurons repair Cas9-induced DNA damage. We discovered that neurons can take weeks to fully resolve this damage, compared to just days in isogenic iPSCs. Furthermore, Cas9-treated neurons upregulated unexpected DNA repair genes, including factors canonically associated with replication. Manipulating this response with chemical or genetic perturbations allowed us to direct neuronal repair toward desired editing outcomes. By studying DNA repair in postmitotic human cells, we uncovered unforeseen challenges and opportunities for precise therapeutic editing.

  • 7 supplemental ZIPs
Cover page: Neuronal DNA repair reveals strategies to influence CRISPR editing outcomes
  • Article
  • Peer Reviewed
UC San Francisco Previously Published Works (2012)
Maternal-fetal cellular trafficking (MFCT) during pregnancy leads to the presence of maternal cells in the fetus and of fetal cells in the mother. Since this process may be altered in cases of pregnancy complications, we asked whether open fetal surgery leads to changes in microchimerism levels. We analyzed maternal and fetal microchimerism in fetuses who underwent open fetal surgery for repair of spina bifida and compared their levels to patients who had postnatal repair and to healthy controls. We found that maternal microchimerism levels were increased in patients who had open fetal surgery compared with controls. In contrast, patients who had fetal intervention at the time of delivery did not demonstrate increased microchimerism. These results suggest that open fetal surgery may alter trafficking. Given the importance of MFCT in maternal-fetal tolerance, we discuss potential implications for the field of preterm labor and transplantation tolerance.
    Cover page: Increased maternal microchimerism after open fetal surgery
    • Thesis
    • Peer Reviewed
    UC San Francisco Electronic Theses and Dissertations (2014)

    The semi-allogeneic fetus derives half of its genetic maternal from the mother. The other half, inherited from the father, leads to the expression of proteins that are foreign to the mother. In danger of potential immune recognition and rejection, the fetus is dependent on maternal immune regulation. Multiple mechanisms are in place to ensure the mother and fetus live in harmony during pregnancy, as outlined in Chapter one. This dissertation discusses what happens to some of these mechanisms during fetal intervention in mice.

    Chapter two focuses on T cell specific mechanisms that prevent maternal T cell activation during pregnancy. These mechanisms include constraint in antigen presentation to maternal T cells, deletion of maternal T cells aware of fetal antigens and the lack of recruitment of maternal T cells to the uterine environment. Fetal intervention in mice results in enhanced antigen presentation with a reduction in apoptosis of activated cells and a more prominent presence of maternal T cells in the uterus. Maternal T cells also play a role in fetal demise (preterm labor) during fetal intervention.

    Chapter three discusses changes in trafficking maternal cells during fetal intervention. Trafficking of maternal cells into fetal blood during normal pregnancy encourages generation of fetal Tregs that can suppress an anti-maternal T cell response. During fetal intervention, the presence of maternal T cells, maternal microchimerism (MMc), increases and may play a role in limiting engraftment of cells transplanted in utero. Because fetal intervention results in preterm labor, changes in maternal microchimerism during fetal intervention may also play a role in mediating fetal rejection during preterm labor. Using a mouse model of preterm labor, we saw enhanced maternal microchimerism in fetal blood. The contribution of maternal cells in fetal blood to the pathogenesis of preterm labor is an open field for further investigation.

    Chapter four deals with the role of maternal Tregs in regulating maternal immune responses during fetal intervention. This chapter more specifically examines maternal antibody production against "conceptus-derived" antigens in the absence of Tregs during normal pregnancy and fetal intervention. Tregs prevent production of maternal antibodies during pregnancy. During fetal intervention, however, maternal antibody production does not increase, even in the absence of Tregs. The presence of "conceptus-derived" antigens in maternal circulation may play a role in preventing detection of maternal antibodies during fetal intervention. Because maternal antibodies do not have an effect on the success of pregnancy, alternative mechanisms may play a role in protecting pregnancy.

    This dissertation discusses how the regulatory mechanisms protecting the semi-allogeneic fetus during pregnancy are disrupted during fetal intervention and may play a role in preterm labor. The results discussed in this dissertation provide support for a novel role of the maternal adaptive immune system in the rejection of the fetus during pregnancy complications. Finally, Chapter five discusses the future directions that have come about because of this thesis work.

      Cover page: Maternal Immune Recognition of the Semi-Allogeneic Fetus During Fetal Intervention in Mice
      • Article
      • Peer Reviewed
      UC San Francisco Previously Published Works (2021)
      α-Thalassemia major (ATM) is a severe disease resulting from deletions in all 4 copies of the α-globin gene. Although it is usually fatal before birth, the advent of in utero transfusions has enabled survival of a growing number of children. Postnatal therapy consists of chronic transfusions or stem cell transplantation, similar to patients with β-thalassemia major. In this review, we discuss the experience with postnatal stem cell transplantation in patients with ATM, as well as the ongoing phase 1 clinical trial of in utero stem cell transplantation for this condition.
        Cover page: Advances in the management of α-thalassemia major: reasons to be optimistic.
        • Article
        • Peer Reviewed
        UC San Francisco Previously Published Works (2014)

        Purpose of review

        Maternal-fetal cellular trafficking (MFCT) is the bidirectional passage of cells between mother and fetus during pregnancy. This results in the presence of fetal cells in the maternal circulation, known as fetal microchimerism, and maternal cells in the fetal circulation, known as maternal microchimerism. The biologic role of this transplacental cellular trafficking during pregnancy is not known, although it has been implicated in development of the fetal immune system, tolerance mechanisms during pregnancy, tissue repair in autoimmune disease and cancer, and immune surveillance.

        Recent findings

        Clinical utility of MFCT has been identified in prenatal testing for aneuploidies and prediction of pregnancy complications. Additionally, this transplacental passage of cells has been implicated in the delicate balance between immunologic priming and tolerance, which can influence the occurrence of autoimmune disease and transplantation outcomes. Ongoing studies are evaluating the utility of microchimerism in predicting the risk of graft rejection in transplantation.

        Summary

        In this review, we will discuss the clinical implications of MFCT in pregnancy, fetal surgery, autoimmune disease, transplantation, and cancer.
          Cover page: Maternal–fetal cellular trafficking
          • Article
          • Peer Reviewed
          UC San Francisco Previously Published Works (2013)
          We report a case of a patient with anal duplication discovered incidentally at 1 year of age. Pre-operative evaluation excluded any complications or associated anomalies. She underwent surgical excision with an excellent outcome.
            Cover page: Anal duplication in a one-year-old girl
            • Article
            • Peer Reviewed
            UC San Francisco Previously Published Works (2014)
            Fetal surgery is a promising strategy to treat fetuses with severe congenital abnormalities but its clinical applications are often limited by preterm labor. In normal pregnancy, multiple mechanisms protect the semi-allogeneic fetus from attack by maternal T cells. Maternal microchimerism (the presence of maternal cells in the fetus) has been suggested to be one mechanism of maternal-fetal tolerance in that it exposes the fetus to non-inherited maternal antigens and leads to the generation of fetal regulatory T cells that can suppress a maternal T cell response. Preterm labor may represent a breakdown of this robust tolerance network. We hypothesized that during inflammation-associated preterm labor, maternal leukocytes cross the maternal-fetal interface and enter the fetal circulation. Consistent with this hypothesis, we found that during preterm labor in mice, the percentage of maternal microchimerism in fetal blood increased and the frequency of fetuses with high levels of trafficking (greater than 0.5%) also increased. Finally, we showed that the maternal leukocytes trafficking into the fetus are primarily Gr-1(+) cells in both syngeneic and allogeneic pregnancy, while T cell trafficking into the fetus specifically increases during allogeneic pregnancies. Our results demonstrate that trafficking of maternal leukocytes during pregnancy is altered during preterm labor. Such alterations may be clinically significant in affecting maternal-fetal tolerance.
              Cover page: Increased maternal T cell microchimerism in the allogeneic fetus during LPS-induced preterm labor in mice
              • Article
              • Peer Reviewed
              UC San Francisco Previously Published Works (2015)
              In utero hematopoietic cell transplantation (IUHCTx) is a promising strategy to circumvent the challenges of postnatal hematopoietic stem cell (HSC) transplantation. The goal of IUHCTx is to introduce donor cells into a naïve host prior to immune maturation, thereby inducing donor-specific tolerance. Thus, this technique has the potential of avoiding host myeloablative conditioning with cytotoxic agents. Over the past two decades, several attempts at IUHCTx have been made to cure numerous underlying congenital anomalies with limited success. In this review, we will briefly review the history of IUHCTx and give a perspective on alpha thalassemia major, one target disease for its clinical application.
                Cover page: In utero hematopoietic cell transplantation for hemoglobinopathies
                • Article
                • Peer Reviewed
                UC San Francisco Previously Published Works (2014)
                Fetal interventions to diagnose and treat congenital anomalies are growing in popularity but often lead to preterm labor. The possible contribution of the maternal adaptive immune system to postsurgical pregnancy complications has not been explored. We recently showed that fetal intervention in mice increases maternal T cell trafficking into the fetus and hypothesized that this process also may lead to increased maternal T cell recognition of the foreign conceptus and subsequent breakdown in maternal-fetal tolerance. In this study, we show that fetal intervention in mice results in accumulation of maternal T cells in the uterus and that these activated cells can produce effector cytokines. In adoptive transfer experiments, maternal T cells specific for a fetal alloantigen proliferate after fetal intervention, escape apoptosis, and become enriched compared with endogenous T cells in the uterus and uterine-draining lymph nodes. Finally, we demonstrate that such activation and accumulation can have a functional consequence: in utero transplantation of hematopoietic cells carrying the fetal alloantigen leads to enhanced demise of semiallogeneic fetuses within a litter. We further show that maternal T cells are necessary for this phenomenon. These results suggest that fetal intervention enhances maternal T cell recognition of the fetus and that T cell activation may be a culprit in postsurgical pregnancy complications. Our results have clinical implications for understanding and preventing complications associated with fetal surgery such as preterm labor.
                  Cover page: Fetal intervention increases maternal T cell awareness of the foreign conceptus and can lead to immune-mediated fetal demise.
                  • Article
                  • Peer Reviewed
                  UC San Francisco Previously Published Works (2014)
                  Fetal interventions to diagnose and treat congenital anomalies are growing in popularity but often lead to preterm labor. The possible contribution of the maternal adaptive immune system to postsurgical pregnancy complications has not been explored. We recently showed that fetal intervention in mice increases maternal T cell trafficking into the fetus and hypothesized that this process also may lead to increased maternal T cell recognition of the foreign conceptus and subsequent breakdown in maternal-fetal tolerance. In this study, we show that fetal intervention in mice results in accumulation of maternal T cells in the uterus and that these activated cells can produce effector cytokines. In adoptive transfer experiments, maternal T cells specific for a fetal alloantigen proliferate after fetal intervention, escape apoptosis, and become enriched compared with endogenous T cells in the uterus and uterine-draining lymph nodes. Finally, we demonstrate that such activation and accumulation can have a functional consequence: in utero transplantation of hematopoietic cells carrying the fetal alloantigen leads to enhanced demise of semiallogeneic fetuses within a litter. We further show that maternal T cells are necessary for this phenomenon. These results suggest that fetal intervention enhances maternal T cell recognition of the fetus and that T cell activation may be a culprit in postsurgical pregnancy complications. Our results have clinical implications for understanding and preventing complications associated with fetal surgery such as preterm labor.
                    Top