Have tissue review sheets out and the animal tissue sheet

Tissues Tissue – a group of cells w/similar structure & function plus the interstitial fluid located between the cells – Histology – the microscopic study of tissue You will be doing this with your fetal pig 3

Tissues  4 basic types of tissues  You will be tested on the identification, function, and general location of each type  Each type of tissue has a specific structure therefore a specific function 4

Tissues SUPPORT COVER MOVE CONTROL

Where does all the dead skin you shed go? It takes about 27 days for the outer layer of skin to shed and be replaced; that works out to 1.5 pounds of skin cells per year.

The ink of tattoos must be injected below the basement membrane.

Tissues often come in layers on the body - superficial cuts on the skin may need to be stitched if they also go through the underlying tissue. WARNING: Graphic picture coming!!! This will definitely need stitches!

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Tissue engineering

Research is being conducted on several different types of tissues and organs, including:  Skin  Cartilage  Blood Vessels  Bone  Muscle  Nerves  Liver  Kidney  etc. etc. etc. Tissue Engineering Tissue Engineering is the development (growth) of tissues or organs to replace or support the function of defective or injured body parts.

Tissue Organization Before a tissue can be developed in vitro, first we must understand how tissues are organized. The basic tenant here is that: “all tissues are comprised of several levels of structural hierarchy” These structural levels exist from the macroscopic level (centimeter range) all the way down the molecular level (nanometer range) – there can be as many as 7-10 distinct levels of structural organization in some tissues or organs

Organization of the Tendon

Organization of the Kidney

Tissue Engineering Scaffolds Biomaterial Scaffolds Materials: – Polymeric: chitosan, alginate, foams, hydrogels, fibers, thin films – Natural: collagen, elastin, fibrin, hydrogels – Ceramic: calcium phosphate based for bone tissue engineering, porous structures – permanent versus absorbable

Tissue Engineering Scaffolds

Culturing of Cells

Sterilization Methods – ultra-violet light, 70% ethanol, steam autoclave, gamma irradiation, ethylene oxide gas Growth Conditions – simulate physiological environment of human! pH 7.4, 37°C, 5% CO 2, 95% relative humidity culture (growth) media replenished periodically Culture (Growth) Media – appropriate chemical environment pH, osmolality, ionic strength, buffering agents – appropriate nutritional environment nutrients, amino acids, vitamins, minerals, growth factors, etc.

Cell Sources Since the ultimate goal of tissue engineering is to develop replacement tissue (or organs) for individuals, the use of autologous (ones own) cells would avoid any potential immunological complications. Various classifications of cells used in tissue engineering applications: – primary cells differentiated cells harvested from the patient (tissue biopsy)  low cellular yield (can only harvest so much)  potential age-related problems – passaged cells Increase of primary cells (can increase population by X)  tendency to either lose potency or de-differentiate with too many passages – Personal stem cells undifferentiated cells can differentiate into functional cell types self-renewal capability (unlimited?)  very rare

Stem Cells Stem cells naturally exist in some tissues (especially those that rapidly proliferate or remodel) and are present in the circulation. There are two predominant lineages of stem cells: – mesenchymal give rise to connective tissues (bone, cartilage, etc.) although found in some tissues, typically isolated from bone marrow – hematopoietic give rise to blood cells and lymphocytes isolated from bone marrow, blood (umbilical cord) Stem cells are rare; bone marrow typically has: – a single mesenchymal stem cell for every 1,000,000 myeloid cells – a single hematopoietic stem cell for every 100,000 myeloid cells

Stem Cells (Mesenchymal)

Stem Cells (Hematopoietic)

Colony-Forming Units (CFUs)

Bioreactors a) Spinner Flask: – semi-controlled fluid shear – can produce turbulent eddies which could be detrimental b) Rotating Wall – low shear stresses, high mass transfer rate – can balance forces to stimulate “zero gravity” c) Hollow Fibre – used to enhance mass transfer during the culture of highly metabolic cells d) Perfusion – media flows directly through construct e) Controlled Mechanics – to apply physiological forces during culture

Bioreactors

nova now c Ted Talk personalized medicine c making a heart from scratch lizard regrows limbs M why can’t we grow a limb! M