Regenerative Medicine Essay31220RegenerativeMedicine EssayKeele university – Guy Hilton Research CenterAbdulaziz Rajeh AlanziMeshari Muteb AlmutairiAbdullah Riyadh Aljandal 25 – Jul - 2011Abstract- Regenerative Medicine aim to repair damaged organs,most often by using stem cells to replace damaged cells.- Stem Cells are biological cells have a unique capacity torenew itself or to give rise to specialized cell type.- Major Types of stem cells are embryonic and adult stemcells, or there is another classification of stem cells :totipotent, pluripotent and unipotent.- Major characteristics of stem cells are Self-renewal,unspecialized and differentiation.- Major applications of stem cells are treating leukemia ,Parkinsons Disease , Heart disease and thalassemia.- Tissue Engineering uses principles from chemistry ,biology , materials science and engineering to developbiological substitutes that can compensate for bodyfunctions that have been lost or impaired as a result ofageing, disease or accident.- Tissue Engineering cells are categorized by theirsource into : autologous , allogenic , cell lines andxenogenic cells.- There are many research areas linked with tissueengineering such as some biomaterials ,biomolecules ,engineering design aspects ,biomechanical aspects of design and informaticsthat support tissue engineering.
Regenerative Medicine Essay31221 Introduction :Regenerative medicine is a wide spired filed holds the promiseof regenerating damaged tissues and organs in the body bystimulating previously irreparable organs to heal themselves , andwe can define regenerative medicine as "Medical interventions thataim to repair damaged organs, most often by using stem cells toreplace damaged cells."Another definition is :"seeks to devise new therapies for patientswith severe injuries or chronic diseases"We can also define stem cells as :"Cells that have both the capacity to self-renew ,make more stemcells by cell division, as well as to differentiate into mature andspecialized cells."(3)So we can say stem cell is the future of regenerative medicine thathas ability to recover and healing a multi-factorial disease such ascongestive heart failure , osteoporosis , Alzheimer’s , Parkinson’sdiseases , severe burns , spinal cord injuries , birth defects , diabetesmellitus ...etc. Stem Cells :First , let us define stem cells as :biological cells have a unique capacity to renew itself (self- renew)to produce more stem cells or to give rise to specializedcell types.o Characteristics of stem cells :1- Self-renewal : so it can make copies of its self .2- Unspecialized : so it remain without any function.3- Differentiated : to any type of cell in human body .o The major types of stem cells:1- Embryonic stem cells :Embryonic stem cells is found in the inner cell massthat is located in early stages of embryo that calledblastocyst .2- Adult stem cells :we can find it in many places in the human body suchas bone marrow , kidney , liver , umbilical cord ,brain , skin , salivary gland and muscle .
Regenerative Medicine Essay31222o Another classification of stem cells:totipotent : embryonic stem cell that can give rise to allthe tissue in the embryo including the extra embryonictissues, placenta, and umbilical cord.Pluripotent : also embryonic stem cell that can give riseto cells derived from all embryonic germ layersmesoderm , endoderm and ectoderm .Unipotent : it is adult stem cell that give rise to just onecell type , however if the tissue in a compromisedsituation and the replacement is must be required ,pluripotent stem cells may become activated to repair thedamage.o Why stem cells is important ?1- Stem cells allow us to know how simple cells growand develop to become a mature cell.2- Stem cells have the ability to regenerate and heal anyloss or damaged any cell or tissue that can not renewthemselves3- As well as one of the importance of the stem cellsthey can be used as treatment for different diseasesuch as Parkinsons disease , Leukemia and skingraft used in severe burns.4- Moreover , stem cells have the potential to regeneratetissue and cure some of the disease like diabetes andmultiple sclerosis.o Properties of embryonic stem cells :-• Derived from the inner cell mass/epiblast of theblastocyst.• Capable of undergoing an unlimited numberof symmetrical divisions without differentiating(long-term self-renewal).
Regenerative Medicine Essay31223• Pluripotent ES cells can give rise to differentiatedcell types that are derived from all three primarygerm layers of the embryo (endoderm, mesoderm,and ectoderm).• Capable of integrating into all fetal tissuesduring development. (Mouse ES cells maintainedin culture for long periods can still generate anytissue when they are reintroduced into anembryo to generate a chimeric animal.)• Capable of colonizing the germ line andgiving rise to egg or sperm cells.• Clonogenic, that is a single ES cell can giverise to a colony of genetically identical cells, orclones, which have the same properties as theoriginal cell.• Expresses the transcription factor Oct-4, whichthen activates or inhibits a host of target genesand maintains ES cells in a proliferative,nondifferentiatingstate.• Can be induced to continue proliferating or todifferentiate.• Lacks the G1 checkpoint in the cell cycle. EScells spend most of their time in the S phase ofthe cell cycle, during which they synthesize DNA.Unlike differentiated somatic cells, ES cells do notrequire any external stimulus to initiate DNAreplication.o Properties of adult stem cells :-• Adult stem cells can proliferate without differentiatingfor a long period (a characteristic referredto as long-term self-renewal), and they can giverise to mature cell types that have characteristicshapes and specialized functions.• Some adult stem cells have the capability todifferentiate into tissues other than the ones fromwhich they originated; this is referred to asplasticity.• To date, published scientific literature indicatesthat adult stem cells have been derived frombrain, bone marrow, peripheral blood, dentalpulp, spinal cord, blood vessels, skeletal muscle,epithelia of the skin and digestive system,cornea, retina, liver, and pancreas; thus, adultstem cells have been found in tissues thatdevelop from all three embryonic germ layers.• Hematopoietic stem cells from bone marrow arethe most studied and used for clinical applicationsin restoring various blood and immune
Regenerative Medicine Essay31224components to the bone marrow via transplantation.There are at least two other populations of adult stem cells thathave been identified from bone marrow and blood.• Several populations of adult stem cells have been identified inthe brain, particularly the hippocampus. Their function isunknown. Proliferation and differentiation of brain stem cellsare influenced by various growth factors.• There are now several reports of adult stem cellsin other tissues (muscle, blood, and fat) thatdemonstrate plasticity. Very few publishedresearch reports on plasticity of adult stem cellshave, however, included clonality studies. That is,there is limited evidence that a single adult stemcell or genetically identical line of adult stemcells demonstrates plasticity.• Rarely have experiments that claim plasticitydemonstrated that the adult stem cells havegenerated mature, fully functional cells or thatthe cells have restored lost function in vivo.o Application :1- Treating Leukemia :Leukemia occur when white blood cells which made inbone marrow begin to grow abnormally .So , we can treat patient with leukemia by transplantstem cells from bone marrow .2- Parkinsons Disease :Parkinsons disease is movement disorder result fromdegenerative of central nervous system because of lackin amount of dopamine which act as neurotransmitter.Treating this disease by using cells that secretedopamine.3- Heart disease :Cardiologists and heart surgeons use vesCell adultstem cell therapy to treat patients suffering fromcoronary artery disease, cardiomyopathy, andcongestive heart failure.4- Thalassemia :Thalassemia is a genetic defect that is result fromdecrease in the synthesis of globin chain that makehemoglobin.The only cure is done by transplant hematopoietic stemcells . Tissue Engineering And Biomaterials :Tissue engineering uses principles from chemistry , biology ,materials science and engineering to develop biological substitutes
Regenerative Medicine Essay31225that can compensate for body functions that have been lost orimpaired as a result of ageing, disease or accident. So we could saythat the main purpose of tissue engineering is to repair or enhancebiological function at the tissue or organ level)etc.skin,bladder,blood vessels,lagecarti,bone(i.e.So when we compare traditional medicine with regenerativemedicine ,traditional medicine is based on replacement of the organwhen there is a destructive disease but regenerative medicine cancure this disease without giving patients entirely new organs.Types of Tissue Engineered ImplantsExamplesMood of ActionTypeBoneBlood VesselsGraft performsprimarily abiomechanicalrole.PhysicalLiver , KidneyGraft perform aphysiologicalrolePhysiologicalPancreaticIsletsUse of cells toproduce soluble,diffusiblecomponentsChemicalSkinGraft performsmore than oneroleCombinationFigure 1 : Types of Tissue Engineered Implants , www.biomed.drexel.eduo Types of Cells :Source of CellsHarvested from patientAutologousCells from donorAllogenicCells which haveundergone geneticmutation which allowsadaptation to indefiniteproliferationCell Lines:Cells from different speciesXenogenicFigure 2 : Source of Cells , www.biomed.drexel.eduCells are often categorized by their source :- Autologous cells : are obtained from same patient and thenthey are re-implanted to the body. But in some cases , thesecells are not available such as with very ill patients or elderlypatients, as well as patients suffering from severe burns, maynot have adequate quantities of autologous cells to create usefulcell lines. The main advantages of these cells are that theautologous cells have the fewest problems in term of pathogentransmission problems and they are always compatible. Butactually there are some disadvantages as well such as its verycostly and take a time to harvest , expand and construct implant.
Regenerative Medicine Essay31226- Allogeneic cells : are obtained from a body of donor of thesame species.- Cell Lines : Cells which have undergone genetic mutationwhich allows adaptation to indefinite proliferation.- Xenogenic cells : are obtained from individuals of anotherspecies.:o Some areas of Tissue Engineering Research:1) Biomaterials: including new biomaterials that aredesigned to guide the growth, differentiation andorganization of cells in the process of forming functionaltissue by providing both physical and chemical cues.2) Cells: including enabling methodologies for thedifferentiation and proliferation of cells, getting theappropriate source of cells such as autologous cells,allogeneic cells, xenogeneic cells, stem cells,3) Biomolecules: including angiogenic factors,differentiation factors, growth factors and bonemorphogenic proteins.4) Engineering Design Aspects: including 2-d cellexpansion, 3-d tissue growth, bioreactors, vascularization,cell and tissue storage and shipping (biological packaging).5) Biomechanical Aspects of Design: including propertiesof native tissues, identification of minimum propertiesrequired of engineered tissues, mechanical signalsregulating engineered tissues, and safety of engineeredtissues6) Informatics to support tissue engineering: gene andprotein sequencing, gene expression analysis, proteinexpression and interaction analysis, quantitative cellularimage analysis, quantitative tissue analysis, in silico tissueand cell modeling, digital tissue manufacturing, automatedquality assurance systems, data mining tools, and clinicalinformatics interfaces. Conclusion :At the present and probably the future also the stem cellsare the future of regenerative medicine by its two majortypes adult and embryonic stem cells. More ever , by itsproperties and important characteristics such asunspecialized , differentiated and self-renewal. Therefore ,we can apply it in many application and treatment as wellsuch as treating leukemia , Parkinsons disease , heart disease, diabetes and thalassemia.
Regenerative Medicine Essay31227On the other hand , tissue engineering also used in manyapplications by obtaining autologous , allogenic , cell lines orxenogenic cells. Therefore , there are many Research areaslinked with tissue engineering such as some biomaterials ,biomolecules ,engineering design aspects , biomechanicalaspects of design and informatics that support tissueengineering.References :1. Ruth Kirschstein, Lana R. Skirboll (June 2001). "Stem Cellsscientific progress and future research direction". Chapter 1-4.Pages :1-422. David M. Panchision (2006)." Regenerative Medicine".Pages :4-113. Mason C, Dunnill P (January 2008). "A brief definition ofregenerative medicine".4. W. W. Minuth, R. Strehl, K. Schumacher (2005). "TissueEngineering". Pages:132-136.5. http://www.tissue-engineering.net – accessed at 19-jul-20116. www.biomed.drexel.edu – accessed at 21-jul-2011