S3 tế bào gốc trưởng thành

Trang 2 Tế bào gốctrưởng thànhAdult Stem Cell or Somatic Stem Cell• Là những tế bào chưa biệt hóa Undifferentiated Cells• Được tìm thấy trong cơ thể sau khi phơi được phát triển hồn chỉn

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Tế bào gốctrưởng thành(Adult Stem Cell or Somatic Stem Cell)• Là những tế bào chưa biệt hóa (Undifferentiated Cells)

• Được tìm thấy trong cơ thể sau khi phơi được phát triển hồn chỉnh (Found

throughout the body after embryonicdevelopment)

• Vai trò chính là duy trì và sữa chữa mô (Multiply by cell division to replenish dyingcells & Regenerate Damaged Tissues

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• Tế bào gốc tạo máu (Hematopoetic Stem

Cells-HSCs)

• Tế bào gốc trung mơ (Mesenchymal tem Cells

-MSCs)

• Tế bào gốc vạn năng cảm ứng (induced

Pluripotent Stem Cells – iPSCs)

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Những thuộc tính của Tế bào gốc trưởng thànhSự sắp đặt chiến lược Sự tự làm mới Số lượng ít Chưa chuyên hóa Ít phân chia Có quần thể phụ

Duy trì tính toàn vẹn của bộ gen (thuyết mạch bất tử)Các marker của tế bào gốc

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Các mô trong cơ thể được tổ chức để giảm thiểu tối đa sự tích lũy các đột biến

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estimated that a single stem cell division ultimately results in the formation of many hundreds of differentiated enterocytes (see Figure 7.24) Therefore, while one might think that stem cells participate in continual cycles of growth and division, the reality is usually much different: the transit-amplifying cells create the great bulk of mitotic activity in many tissues Since the DNA replication occurring during each cell cycle is inherently prone to making errors, this scheme reduces the risk that mutations will accumulate in the genomes of the stem cells.

In many epithelial tissues, the differentiated epithelial cells are especially vulnerable to damage, since they form cell sheets that line the walls of various ducts and cavities containing toxic material In the cases of the colon and the bile duct, the epithelial cells confront fecal contents and highly corrosive bile, respectively The cells lining the alveoli in the lungs cope every day with particulates and pollutants in the air The keratinocytes in our skin are exposed directly to the outside world and hence are liable to sustain several types of damage, including those inflicted by ultraviolet radiation and toxic substances.

The differentiated end-stage cells (see Figure 12.1) in these and other tissues have a finite lifetime and are discarded sooner or later Some cell types may simply age and lose their viability, being worn out from carrying on the active business of the tissue For example, red blood cells have an average lifetime of approximately 120 days, after which they are scavenged by the spleen and broken down and their contents recycled or excreted The epithelial cells in the colon live for 5 to 7 days before they are induced to enter apoptosis and are sloughed off into the lumen of the intestine The keratinoc-ytes in our skin die within 20 to 30 days of being formed, and they are shed continually in small flakes of dead skin (see, for example, Figure 2.6A).

Hence, the transit-amplifying cells may well run an increased risk of sustaining muta-tions because of their high mitotic activity, and their differentiated progeny may often be located in mutagenic environments However, any genetic damage that the transit-amplifying cells and their differentiated progeny have sustained will have little con-sequence for the tissue as a whole: sooner or later, these cells are flushed out of the tissue, and once they die, any mutations they may have accumulated disappear with them (see, however, Supplementary Sidebar 11.2).

Tissues are organized to minimize mutationsb12.01/12.01etc.transit-amplifyingcellshighlydifferentiatedcellsdeathcellfrequent mitosisoccasionalmitosisSTEM CELLCOMPARTMENTshielded fromtoxic agentspost-mitotic cellsexposedto toxic agents

Figure 12.1 Tissue organization and protection of the stem cell genome

The organization of many epithelial tissues seems to conform to the scheme

shown here Each stem cell (blue) divides

only occasionally in an asymmetric fashion to generate a new stem cell daughter and a transit-amplifying daughter These stem cells are often shielded anatomically from toxic agents

The transit-amplifying cells (green)

undergo repeated rounds of growth and division, expanding their populations exponentially Eventually, the products of these cell divisions undergo further differentiation into post-mitotic, highly

differentiated cells (red) The highly

differentiated cells, which are often in direct contact with various toxic agents, are shed with some frequency; hence, any mutant alleles that arise in these cells will be lost, sooner or later, from the tissue This means that the genomes of stem cells are often protected through two mechanisms: infrequent cell

division, and an anatomical barrier that blocks noxious, potentially mutagenic influences.

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Nuôi cấy tế bào đơnNuôi cấy mảnh mô

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Adipose derived Stem cell-ADSC

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Cutting into small pieces

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29

ADD ENZYME &

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Centrifugeto

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Wash with PBS

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Day 0

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DAY 2

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DAY 4

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DAY 6

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DAY 8

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DAY 10

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DIABETIC ULCER TREATMENT

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Những giới hạn của tế bào gốc trưởng thành

•Khơng được thường quy, cần nghiên cứu nhiều

•Những bệnh lý di truyền, ung thư thì những tế bào

gốc vẫn mang những đặc điểm này