Témbongkeun sumber pikeun Sél punca

{{Orphan|date=April 2017}}

[[Gambar:Mouse embryonic stem cells.jpg|right|thumb|300px|Sél sirung [[émbriogenesis mamalia|émbrionik]] [[Mus musculus|beurit]] maké panyiri fluoreséns.]]
'''Sél punca''' atawa '''Sél sirung''' hartina [[sél (biologi)|sél]] mimiti nu ilaharna aya di sakabéh [[organisme]] multisél nu mibanda kamampuh nganyarkeun manéh ku cara meulah diri sarta bisa [[diferensiasi sélulér|dididefensiasi]] jadi rupa-rupa tipe sél. Panalungtikan dina widang sél sirung manusa dimimitian ku papanggihan élmuwan [[Kanada]], [[Ernest McCulloch|Ernest A. McCulloch]] jeung [[James Till|James E. Till]] taun [[1960]]-an.<ref>{{cite journal | author = Becker AJ, McCulloch EA, Till JE | title = Cytological demonstration of the clonal nature of spleen colonies derived from transplanted mouse marrow cells | journal = Nature | volume = 197 | pages = 452-4 | year = 1963 | id = PMID 13970094 }}</ref><ref>{{cite journal | author = Siminovitch L, McCulloch EA, Till JE | title = The distribution of colony-forming cells among spleen colonies | journal = Journal of Cellular and Comparative Physiology | volume = 62| pages = 327-36 | year = 1963 | id = PMID 14086156 }}</ref>

Sél sirung mamalia sacara umum dibagi kana dua kategori: '''[[sél sirung émbrionik]]''' (diturunkeun tina [[blastosis]]) jeung '''[[sél sirung sawawa]]''' (tina jaringan mamalia sawawa). Dina émbrio nu keur mekar, sél sirung bisa ngalaman diferensiasi jadi sagala rupa jaringan émbrio. Dina organisme sawawa, sél sirung jeung sél turunanana meta minangka sistim omé pikeun sél-sél dina awak.

ku sabab bisa tumuwuh sarta [[diferensiasi sélulér|dirobah]] jadi jaringan husus modél otot atawa saraf, sél sirung ditalungtik kabisana pikeun [[terapi sél|natambaan]] kasakit genetik. Kandidat utamana mah nyaéta [[garis sél]] émbrionik, sél sirung émbrionik otolog nu dihasilkeun tina [[kloning terapeutik]], sarta sél sirung tina [[getih ari]] atawa [[sungsum tulang]].<ref>{{cite journal | author = Tuch B | title = Stem cells--a clinical update. | journal = Aust Fam Physician | volume = 35 | issue = 9 | pages = 719-21 | year = 2006 | id = PMID 16969445}}</ref>

== Pasipatan sél sirung ==
=== Pasipatan panangtu ===
Ambahan harti sél sirung anu lega diwatesan ku dua pasipatan: 
* '''''Nganyarkeun manéh''''' (''self-renewal'') - bisa ngalaman sababaraha kali [[daur sél|daur]] meulah sél bari teu ngalaman diferensiasi.
* '''''Poténsi tanpa wates''''' (''unlimited potency'') - bisa ngalaman diferensiasi jadi tipe sél sawawa naon baé.

==== Pedaran poténsi ====
[[Gambar:Stem cells diagram.png|400px|thumb|right|Sél sirung émbrionik pluripotén minangka sél massa jero dina blastosis. Sél sirung bisa jadi jaringan naon baé dina awak, iwal [[bali (anatomi)|bali]]. Ukur sél morula nu totipotén nu bisa jadi sagala rupa sél kaasup bali.]]
''Poténsi'' ngécéskeun poténsial diferensiasi (poténsi pikeun ngalaman diferensiasi jadi rupa-rupa tipe sél) sél sirungna.

* Sél sirung '''[[totipoténsi|totipotén]]''' dihasilkeun tina ngahijina [[sél endog]] jeung [[spérma]]. Sél nu dihasilkeun tina sababaraha beulahan awal endog nu geus dibuahan ogé masih totipotén. Sél-sél ieu bisa ngalaman diferensiasi jadi tipe-tipe sél émbrionik jeung ékstraémbrionik.
* Sél sirung '''[[pluripotén]]''' diturunkeun tina sél totipotén nu bisa ngalaman diferensiasi jadi sél-sél nu diturunkeun tina tilu ''[[germ layer]]''. 
* Sél sirung '''[[multipotén]]''' ukur bisa ngahasilkeun sél anu sakulawarga deukeut kénéh (misalna sél sirung [[hématopoiesis|hématopoietik]] ngalaman diferensiasi jadi sél getih beureum, sél getih bodas, platélét, jsb.).
* Sél '''[[unipoténsi|unipotén]]''' ukur bisa ngahasilkeun hiji tipe sél, tapi masih boga pasipatan nganyarkeun manéh nu ngabédakeun éta sél ti sél non-sirung.
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==Sél sirung émbrionik==
{{utama|Sél sirung émbrionik}}
'''Embryonic stem cell lines''' (ES cell lines) are cultures of cells derived from the epiblast tissue of the inner cell mass (ICM) of a [[blastocyst]]. A blastocyst is an early stage [[embryo]] - approximately 4 to 5 days old in humans and consisting of 50-150 cells. ES cells are [[pluripotent]], and give rise during development to all derivatives of the three primary [[germ layer]]s: ectoderm, endoderm and mesoderm. In other words, they can develop into each of the more than 200 cell types of the adult [[human body|body]] when given sufficient and necessary stimulation for a specific cell type. They do not contribute to the extra-embryonic membranes or the [[placenta]].

When given no stimuli for differentiation, ES cells will continue to divide ''in vitro'' and each [[daughter cell]] will remain pluripotent. The pluripotency of ES cells has been rigorously demonstrated ''in vitro'' and ''in vivo'', thus they can be indeed classified as stem cells.

Because of their unique combined abilities of unlimited expansion and pluripotency, embryonic stem cells are a potential source for regenerative medicine and tissue replacement after injury or disease. To date, no approved medical treatments have been derived from embryonic stem cell research. This is not surprising considering that many nations currently have moratoria on either ES cell research or the production of new ES cell lines.

== Adult stem cells ==
{{main|Adult stem cell}}

[[Image:Stem cells2.png|thumb|160px|'''Stem cell division and differentiation.''' A - stem cell; B - progenitor cell; C - differentiated cell; 1 - symmetric stem cell division; 2 - asymmetric stem cell division; 3 - progenitor division; 4 - terminal differentiation]]

'''Adult stem cells''' are undifferentiated cells found throughout the body that divide to replenish dying cells and regenerate damaged [[biological tissue|tissues]]. Also known as '''[[somatic]]''' (from Greek Σωματικóς, ''of the body'') stem cells, they can be found in children, as well as adults.

A great deal of adult stem cell research has focused on clarifying their capacity to divide or ''self-renew'' indefinitely and their differentiation potential.<ref>{{cite journal | author = Gardner RL | title = Stem cells: potency, plasticity and public perception | journal = Journal of Anatomy | volume = 200 | issue = 3 | pages = 277-82 | year = 2002 | id = PMID 12033732 }}</ref> Many adult stem cells may be better classified as progenitor cells, due to their limited capacity for cellular differentiation.

Nevertheless, specific multipotent or even unipotent adult progenitors may have potential utility in regenerative medicine. The use of adult stem cells in research and therapy is not as [[Stem cell controversy|controversial]] as [[embryonic stem cells]], because the production of adult stem cells does not require the destruction of an [[embryo]]. In contrast with the embryonic stem cell research, more US government funding has been provided for  adult stem cell research.  Adult stem cells can be isolated from a tissue sample obtained from an adult. They  have mainly been studied in [[human]]s and [[model organism]]s such as [[mouse|mice]] and [[rat]]s.

==Lineage==
To ensure self-renewal, stem cells undergo two types of cell division (see ''Stem cell division and differentiation'' diagram). Symmetric division gives rise to two identical daughter cells both endowed with stem cell properties. Asymmetric division, on the other hand, produces only one stem cell and a [[progenitor cell]] with limited self-renewal potential. Progenitors can go through several rounds of cell division before terminally [[cell differentiation|differentiating]] into a mature cell. It is possible that the molecular distinction between symmetric and asymmetric divisions lies in differential segregation of cell membrane proteins (such as [[Receptor (biochemistry)|receptors]]) between the daughter cells, however, there is no evidence for this mechanism.

An alternative theory is that stem cells remain undifferentiated from environmental cues in their particular niche. Stem cells differentiate when they leave that niche or no longer receive those signals. Studies in Drosophila germarium have identified the signals dpp and adherins junctions that prevent germarium stem cells from differentiating<ref>{{cite journal | author = Xie T, Spradling A | title = decapentaplegic is essential for the maintenance and division of germline stem cells in the Drosophila ovary. | journal = Cell | volume = 94 | issue = 2 | pages = 251-60 | year = 1998 | id = PMID 9695953}}</ref><ref>{{cite journal | author = Song X, Zhu C, Doan C, Xie T | title = Germline stem cells anchored by adherens junctions in the Drosophila ovary niches. | journal = Science | volume = 296 | issue = 5574 | pages = 1855-7 | year = 2002 | id = PMID 12052957}}</ref>.

The signals that lead to reprogramming of cells to a embryonic-like state are also being investigated. These signal pathways include several [[transcription factor]]s including the [[oncogene]] [[MYC|c-Myc]]. Initial studies indicate that transformation of mice cells with a combination of these anti-differentiation signals can reverse differentiation and may allow adult cells to become pluripotent.<ref>{{cite journal | author = Takahashi K, Yamanaka S | title = Induction of pluripotent stem cells from mouse embryonic and adult fibroblast cultures by defined factors | journal = Cell | volume = 126 | issue = 4 | pages = 663-76 | year = 2006 | id = PMID 16904174}}</ref> However, need to transform these cells with an oncogene may prevent the use of this approach in therapy.

==Treatments==
{{main|Stem cell treatments}}
Medical researchers believe that stem cell research has the potential to change the face of human disease. A number of current treatments already exist, although the majority of them are not commonly used because they tend to be experimental and not very cost-effective. Medical researchers anticipate being able to use technologies derived from stem cell research to treat [[cancer]], [[parkinson's disease]], [[spinal cord injuries]], and [[muscle]] damage, amongst a number of other diseases, impairments and conditions.
However, there still exists a great deal of social and scientific uncertainty surrounding stem cell research, which could possibly be overcome through public debate and future research.

Stem cells, however, are already used extensively in research, and some scientists do not see cell therapy as the first goal of the research, but see the investigation of stem cells as a goal worthy in itself. <ref>{{cite web | author = Wade N | title = Some Scientists See Shift in Stem Cell Hopes | publisher = New York Times | url=http://www.nytimes.com/2006/08/14/washington/14stem.html | date=2006-08-14 | accessdate=2006-12-28}}</ref>.

==Kontroversi panalungtikan sél sirung==
Panalungtikan sél sirung téh ti anggalna mula teu weléh dirungrum ku kontroversi, utamana mah dina téhnis nyipta jeung migunakeun sél sirungna. Kontroversi panalungtikan [[sél sirung émbrionik]] téh utamana kusabab [[téhnologi]] ayeuna merlukeun ngaruksak [[émbrio|émbrio manusa]] jeung/atawa [[terapi kloning]]. Opponents of the research argue that this practice is a [[slippery slope]] to [[reproductive cloning]] and tantamount to the [[instrumentalization]] of a [[human being]].  Contrarily, medical researchers in the field argue that it is necessary to pursue embryonic stem cell research because the resultant technologies are expected to have significant medical potential, and that the embryos used for research are only those meant for destruction anyway (as a product of [[invitro fertilisation]]).  This in turn, conflicts with opponents holding an [[anti-abortion]] stance, who argue that an embryo is a human being and therefore entitled to dignity even if legally slated for destruction.  The ensuing debate has prompted authorities around the world to seek regulatory frameworks and highlighted the fact that stem cell research represents a [[social]] and [[ethical]] challenge.-->

== Hambalan penting dina panalungtikan sél sirung ==
* '''1960-an''' - [[Joseph Altman]] jeung Gopal Das némbongkeun bukti [[neurogenesis]] sawawa, kagiatan sél sirung dina uteuk; laporan aranjeunna patukang tonggong jeung dogma "euweuh neuron anyar"-na [[Santiago Ramón y Cajal|Cajal]], antukna harita mah teu dianggap
* '''1963''' - [[Ernest McCulloch|McCulloch]] jeung [[James Till|Till]] ngagambarkeun ayana sél nu nganyarkeun manéh dina sungsum tulang beurit
* '''1968''' - [[cangkok]] [[sungsum tulang]] antara dua adi-lanceuk kabukti bisa natambaan [[Severe combined immunodeficiency|SCID]]
* '''1978''' - [[Sél sirung Hématopoietik]] kapanggih dina [[getih ari]] manusa
* '''1981''' - [[Sél sirung émbrionik]] beurit diturunkeun tina [[massa sél jero]]
* '''1992''' - Sél sirung saraf/neural dibudidayakeun ''[[in vitro]]'' minangka neurosfir
* '''1995''' - [[Présidén]] [[Bill Clinton]] nyatujuan [[Amandemén Dickey]] nu nyaram ayana anggaran federal pikeun kagiatan panalungtikan anu maké émbrio manusa.
* '''1997''' - Leukemia kapanggih asalna tina sél sirung hématopoietik, bukti munggaran ayana [[sél sirung kangker]]
* '''1998''' - [[James Thomson (biolog sél)|James Thomson]] saparakanca ngembangkeun [[garis sél sirung]] émbrionik munggaran di Universitas Wisconsin-Madison.
* '''2000-an''' - Sababaraha laporan ngeunaan plastisitas [[sél sirung sawawa]] dipublikasi.
* '''2003''' - Dr. Songtao Shi ti NIH manggihan sumber anyar sél sirung sawawa tina huntu susu<ref>{{cite journal | author=Shostak S | title=(Re)defining stem cells | journal=Bioessays | year=2006 | pages=301-8 | volume=28 | issue=3 | id=PMID 16479584}}</ref>
* '''02 Nopémber 2004''' - [[California]] nyatujuan [[Proposisi 71]] nu nyadiakeun anggaran nagara $3 miliar pikeun panalungtikan sél sirung émbrionik manusa.
* '''2004-2005''' - Panalungtik [[Koréa]] [[Hwang Woo-Suk]] ngaku geus ngembangkeun sababaraha garis [[sél sirung émbrionik]] manusa tina [[oosit]] manusa nu can dibuahan. ka dieunakeun kabuktian garis sél éta palsu.
* '''2005''' - Para panalungtik ti [[Universitas Kingston]], [[Inggris]] ngaku geus manggihan sReséarchers atl sirung kategori tilu, nu dilandih ''cord-blood-derived embryoniclike stem cells'' (CBEs, sél sirung mirip émbrionik), diturunkeun tina getih ari-ari. Kelompok ieu nyebutkeun yén sél-sél ieu bisa didiferensiasi jadi rupa-rupa tipe sél nu leuwih lengkep batan sél sirung sawawa.
* '''2001-2006''' - [[Présidén]] [[George W. Bush]] ngadukung Kongres pikeun nyadiakeun anggaran féderal pikeun panalungtikan sél sirung émbrionik nu kabéhna ampir $100 juta. <!--At the same time, he also enacts laws that restrict federally funded stem cell research on embryonic stem cells to the already derived but dwindling cell lines. Bush also endorsed funding for a total of $250 million dollars for research on adult and animal stem cells.
* '''5 May, 2006''' - [[Rick Santorum]] introduces bill number [[S. 2754]], or the [[Alternative Pluripotent Stem Cell Therapies Enhancement Act.]] into the [[Senate]]
* '''18 July, 2006''' - The U.S. Senate passes the Stem Cell Research Enhancement Act [[H.R. 810]], and votes down Senator Santorum's S.2754.
* '''19 July, 2006''' - [[President]] [[George W. Bush]] vetoes H.R. 810 ([[Stem Cell Research Enhancement Act]]), a bill that would have reversed the Clinton-era law which made it illegal for Federal money to be used for research where stem cells are derived from the destruction of an embryo.
*'''August 2006''' - Cell Journal publishes Kazutoshi Takahashi and Shinya Yamanaka, [http://www.cell.com/content/article/fulltext?uid=PIIS0092867406009767 Induction of Pluripotent Stem Cells from Mouse Embryonic and Adult Fibroblast Cultures by Defined Factors]
* '''07 November, 2006''' - The people of the state of [[Missouri]] vote to protect the possibility of Stem Cell research in their state.
* '''07 January, 2007''' - Scientists at [[Wake Forest University]] led by Dr. [[Anthony Atala]] and [[Harvard University]] report discovery of a new type of stem cell in [[amniotic fluid]].[http://www.nature.com/nbt/journal/v25/n1/abs/nbt1274.html] This may potentially provide an alternative to embryonic stem cells for use in research and therapy. [http://www.boston.com/news/local/massachusetts/articles/2007/01/07/amniotic_fluid_yields_stem_cells_harvard_researchers_report/]-->

== Rujukan ==
* ''[[:en:Stem cell|Stem cell]]'', Wikipédia édisi basa Inggris (per 16 Januari 2007)
<references/>

== Tumbu kaluar ==
* Umum
** [http://stemcells.nih.gov/info/basics/ Stem Cell Basics]
** [http://dels.nas.edu/bls/stemcells/booklet.shtml Understanding Stem Cells: A View of the Science and Issues from the National Academies] {{Webarchive|url=https://web.archive.org/web/20100409081447/http://dels.nas.edu/bls/stemcells/booklet.shtml |date=2010-04-09 }}
** [http://www.sciam.com/article.cfm?chanID=sa006&articleID=000DFA43-04B1-10AA-84B183414B7F0000 Scientific American Magazine (June 2004 Issue) The Stem Cell Challenge]
** [http://www.sciam.com/article.cfm?chanID=sa006&articleID=000B1BED-0C0A-1498-8C0A83414B7F0000 Scientific American Magazine (July 2006 Issue) Stem Cells: The Real Culprits in Cancer?]
** [http://stemcells.nih.gov/ National Institutes of Health]
* Kalawarta ilmiah
** [http://www.stemcells.com STEM CELLS®] {{Webarchive|url=https://web.archive.org/web/20080509155849/http://www.stemcells.com/ |date=2008-05-09 }}
** [http://www.tandf.co.uk/journals/titles/14653249.asp Cytotherapy]
** [http://www.liebertpub.com/publication.aspx?pub_id=9 Cloning and Stem Cells] {{Webarchive|url=https://web.archive.org/web/20071006141053/http://www.liebertpub.com/publication.aspx?pub_id=9 |date=2007-10-06 }}
** [http://www.liebertpub.com/publication.aspx?pub_id=125 Stem Cells and Development] {{Webarchive|url=https://web.archive.org/web/20071007104024/http://www.liebertpub.com/publication.aspx?pub_id=125 |date=2007-10-07 }}
** [http://www.futuremedicine.com/loi/rme Regenerative Medicine]
** [http://www.nature.com/nbt/journal/v25/n1/abs/nbt1274.html Isolation of amniotic stem cell lines with potential for therapy]

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