Harvey Kliman, MD, PhD

Harvey J. Kliman is currently a Research Scientist in the Department of Obstetrics and Gynecology, Yale University School of Medicine and the Director of the Reproductive and Placental Research Unit with a special interest in infertility and pregnancy complications. His five areas of research interest are:

Menstrual Cycle Regulation and Embryo Implantation Research

Menstrual cycle regulation is a critical step in embryo implantation and successfully achieving pregnancy. Since a majority of cases of unexplained infertility may result from implantation failure, there is a need to assess the endometrium accurately for defects that could preclude implantation. Current tools for endometrial evaluation, however, are limited. Based on endometrial expression of cyclin E and p27, we have developed a patented endometrial function test (EFT®) which allows us to evaluate at a molecular level the menstrual cycle regulatory cyclins and to differentiate between normally and abnormally developing, endometrium. Ultimately, we hope this test will prove useful to reproductive endocrinologists in evaluating menstrual cycle irregularities as well as implantation potential. In addition, given that cyclin E and p27 are regulated by estrogen and progesterone, this test may have a role in evaluating the effects of these hormones’ exogenous administration in infertility treatments as well as in other circumstances such as hormone replacement therapy of peri- and post-menopausal women and in clinical conditions that are known to alter or disrupt normal menstrual cycle function. Currently the EFT is used to evaluate patients with infertility and recurrent pregnancy loss. The full potential of these markers will need to be established with prospective, case-controlled multi-center trials that examine different groups of infertility patients to investigate the accuracy of the EFT in predicting pregnancy outcomes in natural cycles, IVF, and donor oocyte patients, work that is currently underway in our laboratory.

Structural Defects in the Placenta Suggest the Presence of Genetic Defects in the Fetus

At the basis of the structure of biological systems are genes that regulate the development of the cells that make up the tissues and organs. We humans start off as a symmetrical ball of cells. Even as our first 50 cells begin to separate themselves into an inner cell mass (which will become the embryo, fetus and, eventually, baby) and the trophoblasts (which will become the placenta), genes are regulating the creation of the developmental axes that will form the basis of the entire organism. Defects in the genes that regulate these processes lead to a wide range of embryonic, fetal and neonatal defects, from minor cosmetic abnormalities, to disasters that terminate pregnancy within a few days to weeks after fertilization. Since the placenta and fetus share the same genome, genetic defects in the fetus are often mirrored in the placenta as abnormal growth patterns. The cellular basis of these placental growth patterns is the dynamic relationship between cytotrophoblast replication and differentiation towards syncytiotrophoblast. We have identified an abnormal growth pattern of the trophoblast layers which appears to be associated with genetic defects in the fetus: trophoblast invaginations. When these deep pits are cut in cross section they appear as trophoblast inclusions. We have shown that compared to the placentas from normal children there is a significantly increased frequency of trophoblast inclusions in cases of known chromosomal diseases, such as trisomy 21, 13 and 18, as well as triploidy (three sets of chromosomes). More recently we have demonstrated an increased frequency of inclusions in cases of subtle genetic diseases, including autism.

Pathway of serotonin and biological action in human trophoblasts

Serotonin (5-hydroxytryptamine; 5-HT) is essential to intrauterine development, but its source is debated. Using immunocytochemistry we have localized 5-HT; its biosynthetic enzyme (tryptophan hydroxylase 1, TPH1); an importer (serotonin transporter, 5-HTT/SERT/SLC6A); other transporters (P-glycoprotein 1 [P-gp/ABCB1], OCT3/SLC22A3 and gap junction connexin-43); and the 5-HT degradative enzyme (monoamine oxidase A, MAOA) in sections of placentas. We found in humans that 5-HT was faintly stained only in first trimester trophoblasts, while TPH1 was not seen at any stage. SERT was expressed in syncytiotrophoblasts and, more strongly, in cytotrophoblasts. MAOA was prominent in syncytiotrophoblasts, OCT3 and gap junctions were stained in cytotrophoblasts, and P-gp was present at the apical surfaces of both epithelia. 5-HT added to cultured placental explants accumulated in the trophoblast epithelium and reached the villus core vessels. Trophoblast uptake was blocked by the SERT inhibitor, escitalopram (Lexapro). Inhibition of gap junctions with heptanol prevented the accumulation of 5-HT in cytotrophoblasts, while blocking OCT3 with decynium-22 and P-gp with mitotane both led to its accumulation in cytotrophoblasts. Reducing 5-HT destruction by inhibiting MAOA with clorgyline increased the accumulation of 5-HT throughout the villus. In the mouse fetus, intravascular platelets stained prominently for 5-HT at day 13.5, while the placenta and yolk sac endoderm were both negative. TPH1 was not detected, but SERT was prominent in these mouse tissues. We conclude from these studies that serotonin is conveyed from the maternal blood stream through syncytiotrophoblasts, cytotrophoblasts and the villus core to the fetus through a physiological pathway that involves at least SERT, gap junctions, P-gp, OCT3, and MAOA. We are currently studying the intracellular pathways and binding partners of serotonin in human placental trophoblasts.

Novel method of determining placental volume reduces the risk of intrauterine growth restriction (IUGR) and intrauterine fetal demise (IUFD)

We have developed a mathematical solution to accurately estimate intrauterine placental volume. Care givers of pregnant women currently only track the growth of the fetus without any insight into the growth of the placenta, despite its importance in prenatal development. The placenta is the critical organ responsible for both respiratory and nutritional support of the fetus. In situations where the placenta is significantly small or large for gestational age, a care giver may not have any warning that the fetus is compromised or near death until it is too late. Fetal complications due to placental abnormalities occur in as many as 20% of pregnancies. Clinical intervention is possible with early detection. This invention allows for assessment of in utero placental volume using three basic measurements: width, height and thickness of the placenta. There are no alternative Currently there are no simple, reliable or convenient methods to determine the volume and/or weight of a placenta prior to delivery available today. We propose to use this method to generate normative data on a large population of pregnant women which can be used to automatically flag abnormal placental size. Such normative data will form the basis for the generation of tables which can be incorporated into future ultrasound devices. This will empower future caregivers to identify and intervene in cases where an IUFD would have been the first indication of any problems. This method will create a “placenta tank” gauge where none has existed.This compromises a health care provider’s ability to assess the state of a pregnancy since the placenta is the critical organ responsible for both respiratory and nutritional support of the fetus. Currently care givers of pregnant women only track the growth of the fetus without any insight into the growth the placenta. In situations where the placenta is significantly small or large for gestational age a care giver may not have any warning that the fetus is compromised or near death until it is too late. This invention teaches the use of mathematical equations to estimate the in utero placental volume using three basic measurements: width, height and thickness of the placenta.

Role of Serotonin in cancer proliferation

Serotonin (5-hydroxytryptamine; 5-HT) is a multifunctional molecule. It is found in the gut in specialized cells that interdigitate with the epithelial cells, functioning as a very primitive neuroendocrine system. It is also found in platelets where it is released at locations of tissue damage, participating in wound healing and tissue repair by inducing localized cell proliferation. In addition to serotonin’s role in wound healing some evidence exists that 5-HT may play a role in tissue regeneration and cancer. We are currently examining the role of serotonin in cancer growth and testing ways to kill cancer cells by inhibiting serotonin synthesis.