Molecular Biology C SSheng Zhao ( 赵晟 ), Biochemistry and Molecular Department of Medical school in Southeast University CCouse QQ Club: ( 分子生物学 C ) WWeb: E or QQQ /MSN/Skype/gChat: MMobile: or Conception, theory, research, and application ——Logic and LIY (Learn It Yourself)

Section 1 : “Sexual” plant ——Plant genes contribute to a sexually transmitted disease. (Horizontal gene transfer) Section 2 : “Natural in vivo system for tissue repair” ——Adult mesenchymal stem cells (Stem cell research) Case 6 : DNAs of our lives ——The role of pharmacogenomics in modern medicine (Clinic medicine research) Chapter 6: Water and Fish (Translational biology and molecular medicine)

Stem cell research

Stem Cells Undifferentiated biological cells Potency for differentiation into specialized cells Self-renewal to produce more stem cells. Found in multicellular organisms.  Embryonic stem cells  Adult stem cells, found in various tissues Three accessible sources of adult stem cells in humans:  Bone marrow  Adipose tissue (lipid cells)  Blood Human embryonic stem cell colony on mouse embryonic fibroblast feeder layer

Self-renewal and differentiation Symmetric stem cell division Asymmetric stem cell division Progenitor division Terminal differentiation A - stem cell; B - progenitor cell; C - differentiated cell

Stem cells in animal models of regeneration Regeneration in Amphibians: Urodeles (salamanders, newts, axolotls) Regeneration in Zebrafish Progenitor division Terminal differentiation

Endoderm, Mesoderm, and Ectoderm

Endoderm specification and differentiation Pancreatic stem cells Specification and patterning of the respiratory system Liver development Endoderm specification

Mesoderm specification and differentiation Epigenetic mechanisms controlling mesodermal specification Mouse kidney development Adult mesenchymal stem cells Adipose

Ectoderm specification and differentiation The cranial sensory nervous system: specification of sensory progenitors and placodes Tooth organogenesis and regeneration Melanocyte stem cells Limbal epithelial stem cells of the cornea Neural crest-derived stem cells

Regenerative medicine The production of cellular therapies requires the optimization of 4 steps: 1.Isolating and culturing 2.Preprogramming of these cells into a pluripotent state. 3.Directed differentiation of those patient- specific pluripotent cells into the cell type relevant to their disease. 4.Techniques for repairing any intrinsic disease-causing genetic defects and transplantation of the repaired, differentiated cells into the patient.

Methods of nuclear reprogramming (NT)

Oocyte / Zygote injection

Progress towards the elimination of ES nucleus following fusion Cre-LoxP for “Chromosome Elimination Cassette” (CEC)

The epigenetic landscape and its implications for direct reprogramming (A) A Waddington-inspired schematic of the epigenetic landscape. (B) A closer look at the path a pluripotent cell might take as it differentiates into a neuron, passing through a number of intermediate progenitor states of varying stability on the way. (C) The process of direct reprogramming, like chemical catalyst, implicates a restructuring of the epigenetic landscape.

Reprogramming capacity in NT depends on cell-cycle status Hard for a germinal-vesicle stage oocyte or pronuclear zygote with somatic chromatin. Easier for the MII-arrested oocyte or a zygote arrested with a drug in the first mitosis allows for the generation of cloned mice and ntES cells.

Mesenchymal stem cells (MSCs) Multipotent stromal cells that can differentiate into a variety of cell types 1.Osteoblasts (bone cells) 2.Chondrocytes (cartilage cells) 3.Adipocytes (fat cells) Typical gross appearance of a tubular cartilaginous construct engineered from amniotic mesenchymal stem cells Relatively easy to culture and maintain in vitro Low immune reacts The mesenchymal stem cells can be activated and mobilized if needed. Intravenous transplantation (graft versus host disease and sepsis) Direct injection or placement of cells into a site in need of repair Possible tumor formation

Disadvantages or potential challenge Immune rejection Pluripotency in certain stem cells could also make it difficult to obtain a specific cell type. Tumor formation: pluripotency is linked to tumor formation especially in embryonic stem cells, fetal proper stem cells, induced pluripotent stem cells. Both adult and embryonic stem cells could differentiate into a cancerous form Heterogeneous: Makes it difficult to obtain exact cell type needed, because not all cells in a population differentiate uniformly. Undifferentiated cells can create tissues other than desired types.

Stem cells, cancer, and epigenetics

Progenitor cells