Fyziologie růstu vlasů

Hair natural color

• Darker hair
• More carbohydrates
• Less oxygen
• Blonder hair
• More oxygen than carbohydrates
• Medium-dark hair
• Up to 50.65 percent of carbohydrates
• 6.36 % of hydrogen
• 17.14 % of nitrogen
• 5.0 % of sulfur
• 20.85 % of oxygen

Melanin

• Pigment contained in hair
• protein complex combinations (triptofan, pirol, etc.)
• Contains nitrogen, sulfur, oxygen and a small amount of iron and arsenic
• Melanin component concentration ratio
• Determines each unique human hair color

Melanin receptor-1 receptor (MC1R) gene

• Crucial factor in human hair color and skin color

MC1R

• Expressed in the melanocyte or melanin cell tumor
• Receptor of alpha-melanocyte stimulating hormone (alpha-MSH)
• Alpha-MSH via MC1R could activate the adenylate cyclase (AC)
• May lead to increasing intracellular cyclic adenosine monophosphate (cAMP)
• Could activate tyrosinase enzyme though protein kinase A (PKA), a rate limiting enzyme
• Classic way of synthesis of melanin by alpha-MSH in melanocyte [26]

Počet vlasů

• U každého různý cca 180 - 330 na jeden čtvereční cm vlasaté plochy.
• Tmavovlasí lidé mají asi 80 až 100 tisíc vlasů
• Plavovlasí až o třetinu více

Růstové fáze

• Délka života lidského vlasu se pohybuje od 2 do 5 let.
• Během této doby prochází vlas několika fázemi:

1) Růstové období

• První a zároveň nejdelší období
• Trvá několik let.
• Vlas vyvíjí a roste
• V růstové fázi se nachází asi 80 procent našich vlasů. [4]

2) Fáze přechodná

• Krátké časové období (několik týdnů)
• Přicházejí o výživu
• Zastavují svůj růst
• Odumírají
• Rychle nastupuje třetí fáze

3) Konečná fáze

• Odumřelé vlasy se v průběhu několika měsíců dostávají do svrchních vrstev kůže a postupně vypadávají.
• Normálně ve třetí fázi až pětina vlasového porostu
• Každý z nás přijde každý den asi o stovku odumřelých vlasů
• Jejich místa nahrazují nové, které vznikají ve vlasových cibulkách v hloubce kůže.
• Růst, odumírání a výměna vlasů probíhají celý život už od dětství.
• K nejvýraznějším změnám ve vlastnostech a vzhledu vlasů dochází do puberty.

Rychlost růstu

• V průměru vyrostou za den asi o 0,3 milimetru, tj. 1 centimetr za měsíc.
• Rychlost je určena geneticky a zůstává víceméně stabilní.
• Za pocit, že Vám někdy rostou vlasy rychleji, může spíš typ Vašeho účesu

Regulace růstu vlasu

• By many proteins and factors
• Cell proliferation and migration are the essential factors for hair growth [27]
• Ki67 marker is expressed only in the active phases of cell growth, such as the G1, S, and G2 phases and mitosis [27]

Dermal papilla cells (DPCs)

• Major hair components
• Secrete a number of growth factors
• Modulate the proliferation of follicular epithelium and follicle development [28]
• Size of DPC is well correlated with
• The hair growth
• The number of DPC
• Increases in the early anagen stage [28]

Keratinocyte

• Pivotal roles in hair follicle and hair shaft
• At early anagen are activated
• Subsequently fasted proliferating cells
• Make hair bulb structure with hair matrix surrounding DPC before activation of hair follicle stem cell [28]

Beta-catenin

• Important component in Wnt signaling pathways
• Indispensable to skin replacement and hair follicle development[26]

Wnt/beta-catenin pathway

• Important role in the hair growth cycle
• Beta-catenin markedly activated during anagen phase
• Initiation of hair follicle formation
• Stimulating hair growth and differentiation [28]
• Beta-catenin knock-out mice
• Catagen and telogen phases induce premature condition
• Regeneration of hair follicle is the failure [28]
• Absence of Wnt:
• Beta-catenin is ordinarily phosphorylated in the cytoplasm by glycogen synthase GSK-3b (beta) and kinase-3b
• Tagged by an ubiquitin
• Dissolved by the proteasome
• Wnt protein binds to receptors of Frizzled family
• Beta-catenin is accumulated in the cytoplasm
• Translocated into the nucleus
• Induction of growth signals for hair follicle progenitors
• Promoting differentiation of hair follicular keratinocyte [28]
• GSK-3
• Key regulator in beta-catenin pathway
• Many researchers have reported chemicals and natural extracts that stimulate hair growth by targeting the beta-catenin pathway [28]
• GSK-3beta inhibitor
• Enhances hair-inducing ability
• Stabilization of ß-catenin
• Elevated the alkaline phosphatase
• Elevated insulin-growth factor-1 gene expressions [28]
• Hair cycle regeneration and anagen phase maintenance are ß-catenin dependent [28]
• Activation of ERK1/2 and Akt is related to beta-catenin signaling pathway
• Their phosphorylation increased beta-catenin/TCF complex
• Through inactivation of GSK3beta [28]
• Phosphorylation of ERK1/2 and/or Akt
• Induces activation of beta-catenin signaling pathway [28]

SHH - Sonic Hedgehog

• Significantly facilitate telogen stage
• Facilitate catagen stage hair follicles entering into anagen stage
• Promoting hair growth

HGF - Hepatocyte growth factor

• Facilitate hair follicles to enter the anagen stage when injected to newborn mice

IGF-1 - Insulin-like growth factor-1

• Could promote hair follicle growth
• Could maintain the hair follicles' growth in in vitro cultivation of human hair follicle cells

FGF-7 - Fibroblast growth factor-7

• Obvious adjustment to the hair growth
• Could promote hair to enter the anagen stage and increase hair follicles amounts

Vascular endothelial growth factor (VEGF)

• Induce the formation of blood vessels around hair follicles
• Also promote directly the dermal papilla cells proliferation

Lymphatic enhancement factor (Lef-1)

• Key nuclear transcription factor in the Wnt/beta-catenin signaling pathways
• Whisker hair follicles disappear completely and back skin hair follicles growth stops in Lef-1 knockout mice
• Important role in regulating the hair follicle growth

SCF - Stem cell factor

• Role in preserving stem cells
• Participating in the growth of hair follicles
• Detectable in the anagen stage [27]
• Induction of endothelin-1 and SCF correlated with the regeneration of hair follicles [28]

ERK1/2 and Akt pathway

• Activation promoted the proliferation and survival of DPC (dermal paila cells)
• Activated by mitogens in all types of mammalian cells
• Key roles in cell growth [28]
• Akt
• Antiapoptotic molecule [28]

Tvar vlasu

• Standard “cold” perm (trvalá)
• Hair is put into curlers and the reducing agent ammonium thioglycolate is added
• Disulfide bonds break
• Keratin molecules are free to move around and adjust to the shape of the curl
• “neutralizer,” such as hydrogen peroxide is added
• Reverse the effect of the reducing agent
• New disulfide bonds form
• Keratin molecules are locked into the shape of the curls