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 Erhan Ayşan

Erhan Aysan MD Prof, Department of General Surgery, Division of Endocrine Surgery

He was born in Istanbul in 1968. He completed his pre-university education in Istanbul (Besiktas Barbaros Primary School, Nisantası Secondary School, Sisli High School). He graduated from Istanbul University, Cerrahpaşa Faculty of Medicine in 1994. He worked as a research fellow at Boston University for a while. He was a general surgeon in 1999, an associate professor in 2006, and a professor in 2011. He is the chief of Bezmialem Vakif University Department of General Surgery and Division of Endocrine Surgery. He is the coordinator of Bezmialem Vakif University  department of the Scientific Research Projects. He founded Turkey's first Endocrinology Department, Endocrinology graduate program, Endocrinology & Metabolism Research Laboratuary and established the world's first multidisciplinary parathyroid transplantation center. He has more than 100 manuscripts, more than 10 patents and 5 books. 

In our Endocrinology Research Laboratory we use state-of-the-art molecular biology techniques to understand Parathyroid cell's Biology and recombinant parathyroid hormone Production. Our team consists of researchers from different disciplines who are dedicated to their work and have high motivation. Our research interests are mainly shaped by microbial recombinant parathyroid hormone production systems. So we decided to branch out our studies from these studies.

1)      Biopharmaceuticals: Biopharmaceuticals are the most widely used drug types in the world. In 2017, 3 of the top 5 drugs sold were biological drugs. Moreover, recombinant human hormones are one of the most used biological drug groups in the world. The main mission of our laboratory is to understand the basic biology of parathyroid cells and to work on the recombinant parathyroid hormone production. We use Pichia pastoris cells as the basic recombinant protein production platform. Our production steps are progressing in the form of genetic fragment design, plasmid design, optimization of post-translational processes, construction of necessary co-expressions, formation of stable expression levels, creation of recombinant parathyroid hormone specific purification system and animal testing to create the appropriate formulation. At the same time, we will follow the behavior of our cells and their expression profile in a large-scale 5-liter fermenter optimization. We are working to reveal higher analogue variants with modifications we have made on the parathyroid hormone that we intend to produce.

2)      Probiotic Engineering For Drug Delivery: Bioengineered probiotics represent the next generation of whole cell– mediated biotherapeutics. Advances in synthetic biology, genome engineering, and DNA sequencing and synthesis have enabled scientists to design and develop probiotics with increased stress tolerance and the ability to target specific pathogens and their associated toxins, as well as to mediate targeted delivery of vaccines, drugs, and immunomodulators directly to host cells. In our laboratory we work on delivery of rekombinant parathyroid hormone via probiotic Saccharomyces boulardii. We are also working on extracellular secretion signals of cells to enable Saccharomyces boulardii cells, known as probiotics, to produce recombinant parathyroid hormone in higher amounts in the gastrointestinal tract.

3)      Metabolic Engineering For Small Drug Molecule Production: Metabolic engineering has been defined as the redirection of metabolic pathways using genetic manipulation. Today, metabolic engineering plays an important role in the generation of fuels from renewable resources, the conversion of agricultural raw materials into specialty chemicals, and the discovery, development and scale-up of therapeutically useful products. The production of a new or existing drug in a heterologous host generally involves the introduction of several genes in a biosynthetic cascade. In principle, metabolic engineering is much more than introducing several genes into the cell, it often involves carefully balancing the genes in the new metabolic pathway. We want to integrate different kind of plant biosynthetic pathways to produce their final active molecules in the yeast Pichia pastoris.


4)      Systems and Synthetic Biology: Systems Biology includes the study of interaction genetic, proteomic and metabollic networks and, in particular, their dynamic and spatiotemporal aspects. It typically requires the import of concepts from across the disciplines and crosstalk between theory, modelling and simulation. The basis of Systems Biology is the discovery of the design principles of Life. The logical next step is to apply these principles to synthesize biological systems. This engineering of biology is the ultimate goal of Synthetic Biology, the rational conception and construction of complex systems based on, or inspired by, Biology. We try to create boolean logic synthetic genetic circuits for our recombinant parathyroid hormone produced yeast cells for switchable and modular production. To create dynamic logic gates we are preparing to use the CRISPR-Cas9 technology for genome engineering. In addition, direct transcriptomic and genomic studies are underway to understand parathyroid cell biology.


From Bench to Bedside​
In addition, our team particularly focus on the parathyroid allotransplantation. In Turkey, all organ and tissue transplantations are carried out with the permission of the National Scientific Board for Transplantation, which is part of the Turkish Ministry of Health. Our Parathyroid Transplantation Unit is the first and unique center in Turkey that was officially permitted and approved to conduct parathyroid allotransplantation

For detailed information, please see, http://paratirnakil.bezmialemhastanesi.com/tr/Sayfalar/index.aspx​