Biochemical Technologies

• Tissue engineering • Nanobiotechnology

Tissue engineering • “Tissue Engineering is an

interdisciplinary field that applies principles of engineering and life sciences towards the development of biological substitutes that aim to maintain, restore, or improve tissue function.”

• Tissue Engineering is the in vitro development (growth) of tissues or organs to replace or support the function of defective or injured body parts

• Tissue Engineering is the in vitro development (growth) of tissues or organs to replace or support the function of defective or injured body parts.

Skin Cartilage Blood Vessels Bone Muscle Nerves Liver KidneyDental etc. etc.

Cellular CommunicationsCell-to-Cell Contact:

o some membrane receptors are adhesive molecules• adherent junctions and desmosomes

o other serve to create junctions between adjacent cells allowing for direct cytoplasmic communication

• gap junctions• 1.5-2 nm diameter and only allow transport of small

molecules ~1 kDa

Cellular Communications•Cell-ECM Interactions:

o ECM is multifunctional and also provides a substrate that cells can communicate

o since cells synthesize the ECM, they can modify the ECM to elicit specific cellular responses

o several specialized receptors that allow for cell-ECM interactions

• integrins, CD44, etc.• also a mechanism by with cells respond to

external stimuli (“mechanical transducers”)

Cells• Cells are taken from the healthy tissue of what tissue is being

created.o Skin cells for skin, bladder cells for bladder, etc.

• Cells taken from donor or patient themselveso Autologous-donor and patient are the sameo Allogenic-cells from another persono Xenogenic-cells from another species

• Separated and screened for pathogens and disease• Placed onto scaffolds

•Stem cells are the bodys "master" cells that regenerate the body many cells, tissues, and organs. Most cells in your body can only make new cells of the same type - blood cells make blood cells, skin cells make more skins cells and so on. Stem cells are unique not only because they can turn into many different types of cells - a stem cell might create blood, kidney, heart, or bone for example - but also because they can divide many more times than other cells.

Stem cells

What Are Stem Cells?

Stem cells are the raw material from which all of the body’s mature, differentiated cells are made. Stem cells give rise to brain cells, nerve cells, heart cells, pancreatic cells, etc.

Stem Cell – Definition A cell that has the

ability to continuously divide and differentiate (develop) into various other kind(s) of cells/tissues

Components of Tissue Engineering

• Cells• Matrix or Scaffold• Bioreactor• Cytokines and Growth Factors

Stem cells are different from other cells of the body in that they have the ability to differentiate into other cell/tissue types. This ability allows them to replace cells that have died. With this ability, they have been used to replace defective cells/tissues in patients who have certain diseases or defects.

Types of stem cells

There are two broad types of stem cells: embryonic stem cells and adult stem cells. While there has been much debate on the ethical issues surrounding the use of embryonic stem cells, adult stem cells are free of this controversy and only adult stem cells, to date, have been used to treat people.

Types of stem cells (conti..)

Embryonic stem cells• “Human embryonic stem (ES) cells are cultured

cell lines derived from the inner cell mass of the blastocyst that can be grown indefinitely in their undifferentiated state, yet also are capable of differentiating into all cells of the adult body.” Two sourcesoFertilized egg from in vitro fertilizationoOvum that has had nucleus removed and nuclear

material injected from intended recipient of final tissue product (reproductive/therapeutic cloning)

• Very controversial

Adult stem cells

• Found in:oUmbilical cord blood/tissueoAdult brain, blood cornea, retina, heart, fat,

skin, dental pulp, bone marrow, blood vessels, skeletal muscle and intestines

The most commonly known source of adult stem cells is bone marrow, which contains both hematopoietic stem cells (also found in cord blood)and mesenchymal stem cells (also found in teeth).

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:omesenchymal

• give rise to connective tissues (bone, cartilage, etc.)

• although found in some tissues, typically isolated from bone marrow

hematopoieticgive rise to blood cells and lymphocytesisolated 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 cellsa single hematopoietic stem cell for every 100,000 myeloid cells

Stem Cells (Mesenchymal)

Stem Cells (Hematopoietic)

Scaffolding

• Act as Extra Cellular Matrix for cells• Function: Delivery of cells to desired sites, define

space for formation, guide development with appropriate function

• Needs to be able to control the structure and function of tissue in a predesigned manner.

• Ideally they are biocompatible and biodegradable, without provoking inflammation or toxicity in the body.

Tissue Engineering Scaffolds•Biomaterial Scaffolds Materials:

o polymeric• chitosan, alginate, etc.• foams, hydrogels, fibres, thin films

o natural• collagen, elastin, fibrin, etc.• hydrogels

o ceramic• calcium phosphate based for bone tissue engineering• porous structures

o permanent versus resorbable• degradation typically by hydrolysis• must match degradation rate with tissue growth

•Chemical and Physical Modifications:o attachment of growth factors, binding sites for integrins, etc. nanoscale

physical features

Bioreactors

• System where conditions are closely controlled to permit and induce a certain behavior in living cells or tissues

• Provide controlled and steady flow of cell media• Factors necessary for cell growth:

o pH, temp. pressure, nutrient supply, waste removal• Types of Bioreactors

o Spinner Flasks, Rotating Vessels, Hollow Fiber, Perfusion reactors

Culturing of Cells•Sterilization Methods

o ultra-violet light, 70% ethanol, steam autoclave, gamma irradiation, ethylene oxide gas

•Growth Conditionso simulate physiological environment

• pH 7.4, 37°C, 5% CO2, 95% relative humidity

• culture (growth) media replenished periodically•Culture (Growth) Media

o appropriate chemical environment• pH, osmolality, ionic strength, buffering agents

o appropriate nutritional environment• nutrients, amino acids, vitamins, minerals, growth

factors, etc.

Tooth anatomy

www.vivianbaedds.com

TYPES OF DENTAL STEM CELLS

• Dental Pulp Stem Cells (DPSCs)

• Stem cells from human exfoliated

deciduous teeth (SHEDs)

• Periodontal Ligament (PDLSCs)

• Dental follicle stem cells (DFSCs)

• Apical papilla (SCAPs)

Adapted from http://ww.bioscience.org.

INDICATION

1.Dental tissue repair: dental stem cells are currently considered to offer potential for tissue regeneration

Periodontal regeneration: The periodontium is a set of specialized tissues that surround and support the teeth to maintain them in the jaw.Periodontitis is an inflammatory disease that affects the periodontium and results in irreversible loss of connective tissue attachment and the supporting alveolar bone.

Regeneration of dental pulp inimmature tooth Dental pulp needs to be removed when it becomesinfected, and this is particularly problematic for root pulpthat requires endodontic (root canal) treatment.

Whole tooth regeneration:

SummaryTooth Stem Cells Therapeutic PotentialThe ultimate goal of tooth regeneration is to replacethe lost teeth. Stem cell-based tooth engineering isdeemed as a promising approach to the making ofa biological tooth (bio-tooth). Dental pulp stem cells(DPSCs) represent a kind of adult cell colony whichhas the potent capacity of self-renewing andmultilineage differentiation. A bio-tooth made fromautogenous DPSCs should be the best choice forclinical tooth reconstruction.

Thank you