Cell. 2011 Sep 2;146(5):761-71.
Adipocyte lineage cells contribute to the skin stem cell niche to drive hair cycling.
Festa E, Fretz J, Berry R, Schmidt B, Rodeheffer M, Horowitz M, Horsley V.
Source
Departments of Molecular, Cell, and Developmental Biology, Yale University, 219 Prospect St., New Haven, CT 06520, USA.
Abstract
In mammalian skin, multiple types of resident cells are required to create a functional tissue and support tissue homeostasis and regeneration. The cells that compose the epithelial stem cell niche for skin homeostasis and regeneration are not well defined. Here, we identify adipose precursor cells within the skin and demonstrate that their dynamic regeneration parallels the activation of skin stem cells. Functional analysis of adipocyte lineage cells in mice with defects in adipogenesis and in transplantation experiments revealed that intradermal adipocyte lineage cells are necessary and sufficient to drive follicular stem cell activation. Furthermore, we implicate PDGF expression by immature adipocyte cells in the regulation of follicular stem cell activity. These data highlight adipogenic cells as skin niche cells that positively regulate skin stem cell activity, and suggest that adipocyte lineage cells may alter epithelial stem cell function clinically.
PMID:
21884937
[PubMed – in process] Exp Dermatol. 2004 Oct;13(10):621-9.
The role of BMP signalling in the control of ID3 expression in the hair follicle.
O’Shaughnessy RF, Christiano AM, Jahoda CA.
Source
Dermatology Department, Columbia University, New York, NY, USA.
Abstract
Both the production of the hair shaft in anagen and the initiation of a new hair cycle at telogen are the result of reciprocal interactions between the dermal papilla and the overlying epithelial cells. Secreted factors, such as those of the bone morphogenetic protein (BMP) family, play a crucial role in moderating these interactions. Analysis of hair follicles in different stages of the hair cycle showed that BMP signalling was only active during anagen and again during telogen. During catagen, no BMP signalling occurred in the dermal papilla. ID3, a gene expressed in the dermal papilla of both vibrissa and pelage follicles, is a BMP target, and as such, we found that ID3 was expressed from the earliest stages of morphogenesis. During the hair cycle, ID3 was only expressed in the dermal papilla at middle anagen and telogen. To test the significance of ID3 expression in the dermal papilla, we cultured dermal papilla cells and found that ID3 expression fell significantly after a single passage. ID3 expression was returned to in vivo levels in low- and high-passage cells by culturing to high confluence or by the addition of BMP4. These studies reinforce the requirement for active BMP signalling and cell-cell contacts in the dermal papilla during specific stages in the hair cycle.

Cell. 2011 Jan 7;144(1):92-105.
Dynamics between stem cells, niche, and progeny in the hair follicle.
Hsu YC, Pasolli HA, Fuchs E.
Source
Howard Hughes Medical Institute, The Rockefeller University, New York, NY 10065, USA.
Abstract
Here, we exploit the hair follicle to define the point at which stem cells (SCs) become irreversibly committed along a differentiation lineage. Employing histone and nucleotide double-pulse-chase and lineage tracing, we show that the early SC descendents en route to becoming transit-amplifying cells retain stemness and slow-cycling properties and home back to the bulge niche when hair growth stops. These become the primary SCs for the next hair cycle, whereas initial bulge SCs become reserves for injury. Proliferating descendents further en route irreversibly lose their stemness, although they retain many SC markers and survive, unlike their transit-amplifying progeny. Remarkably, these progeny also home back to the bulge. Combining purification and gene expression analysis with differential ablation and functional experiments, we define critical functions for these non-SC niche residents and unveil the intriguing concept that an irreversibly committed cell in an SC lineage can become an essential contributor to the niche microenvironment.

Cell Stem Cell. 2009 Feb 6;4(2):155-69.
A two-step mechanism for stem cell activation during hair regeneration.
Greco V, Chen T, Rendl M, Schober M, Pasolli HA, Stokes N, Dela Cruz-Racelis J, Fuchs E.
Source
Howard Hughes Medical Institute, The Rockefeller University, New York, NY 10065, USA.
Erratum in
• Cell Stem Cell. 2009 May 8;4(5):464.
Abstract
Hair follicles (HFs) undergo cyclic bouts of degeneration, rest, and regeneration. During rest (telogen), the hair germ (HG) appears as a small cell cluster between the slow-cycling bulge and dermal papilla (DP). Here we show that HG cells are derived from bulge stem cells (SCs) but become responsive quicker to DP-promoting signals. In vitro, HG cells also proliferate sooner but display shorter-lived potential than bulge cells. Molecularly, they more closely resemble activated bulge rather than transit-amplifying (matrix) cells. Transcriptional profiling reveals precocious activity of both HG and DP in late telogen, accompanied by Wnt signaling in HG and elevated FGFs and BMP inhibitors in DP. FGFs and BMP inhibitors participate with Wnts in exerting selective and potent stimuli to the HG both in vivo and in vitro. Our findings suggest a model where HG cells fuel initial steps in hair regeneration, while the bulge is the engine maintaining the process.

Nature. 2008 Jan 17;451(7176):340-4.
Cyclic dermal BMP signalling regulates stem cell activation during hair regeneration.
Plikus MV, Mayer JA, de la Cruz D, Baker RE, Maini PK, Maxson R, Chuong CM.
Source
Department of Pathology, Keck School of Medicine, University of Southern Mississsippi, Los Angeles, Mississsippi 90033, USA.
Abstract
In the age of stem cell engineering it is critical to understand how stem cell activity is regulated during regeneration. Hairs are mini-organs that undergo cyclic regeneration throughout adult life, and are an important model for organ regeneration. Hair stem cells located in the follicle bulge are regulated by the surrounding microenvironment, or niche. The activation of such stem cells is cyclic, involving periodic beta-catenin activity. In the adult mouse, regeneration occurs in waves in a follicle population, implying coordination among adjacent follicles and the extrafollicular environment. Here we show that unexpected periodic expression of bone morphogenetic protein 2 (Bmp2) and Bmp4 in the dermis regulates this process. This BMP cycle is out of phase with the WNT/beta-catenin cycle, thus dividing the conventional telogen into new functional phases: one refractory and the other competent for hair regeneration, characterized by high and low BMP signalling, respectively. Overexpression of noggin, a BMP antagonist, in mouse skin resulted in a markedly shortened refractory phase and faster propagation of the regenerative wave. Transplantation of skin from this mutant onto a wild-type host showed that follicles in donor and host can affect their cycling behaviours mutually, with the outcome depending on the equilibrium of BMP activity in the dermis. Administration of BMP4 protein caused the competent region to become refractory. These results show that BMPs may be the long-sought ‘chalone’ inhibitors of hair growth postulated by classical experiments. Taken together, results presented in this study provide an example of hierarchical regulation of local organ stem cell homeostasis by the inter-organ macroenvironment. The expression of Bmp2 in subcutaneous adipocytes indicates physiological integration between these two thermo-regulatory organs. Our findings have practical importance for studies using mouse skin as a model for carcinogenesis, intra-cutaneous drug delivery and stem cell engineering studies, because they highlight the acute need to differentiate supportive versus inhibitory regions in the host skin.
PMID:
18202659
[PubMed – indexed for MEDLINE] PMCID: PMC2696201
Genes Dev. 2008 Apr 15;22(8):976-85.
More than one way to skin . . .
Fuchs E, Horsley V.
Source
Howard Hughes Medical Institute, Laboratory of Mammalian Cell Biology and Development, The Rockefeller University, New York, New York 10065, USA. fuchslb@rockefeller.edu
Abstract
Epithelial stem cells in the skin are specified during development and are governed by epithelial-mesenchymal interactions to differentially adopt the cell fates that enable them to form the epidermis, hair follicle, and sebaceous gland. In the adult, each of three epithelial lineages maintains their own stem cell population for self-renewal and normal tissue homeostasis. However, in response to injury, at least some of these stem cell niches can be mobilized to repair an epithelial tissue whose resident stem cells have been damaged. How do these stem cell populations respond to multiple signaling networks, activate migration, and proliferation, and differentiate along a specific lineage? Recent clues add new pieces to this multidimensional puzzle. Understanding how these stem cells maintain normal homeostasis and wound repair in the skin is particularly important, as these mechanisms, when defective, lead to skin tissue diseases including cancers.

BMP signaling in dermal papilla cells is required for their hair follicle-inductive properties.
Rendl M, Polak L, Fuchs E.
Source
Howard Hughes Medical Institute, Laboratory of Mammalian Cell Biology and Development, The Rockefeller University, New York, New York 10021, USA.
Abstract
Hair follicle (HF) formation is initiated when epithelial stem cells receive cues from specialized mesenchymal dermal papilla (DP) cells. In culture, DP cells lose their HF-inducing properties, but during hair growth in vivo, they reside within the HF bulb and instruct surrounding epithelial progenitors to orchestrate the complex hair differentiation program. To gain insights into the molecular program that maintains DP cell fate, we previously purified DP cells and four neighboring populations and defined their cell-type-specific molecular signatures. Here, we exploit this information to show that the bulb microenvironment is rich in bone morphogenetic proteins (BMPs) that act on DP cells to maintain key signature features in vitro and hair-inducing activity in vivo. By employing a novel in vitro/in vivo hybrid knockout assay, we ablate BMP receptor 1a in purified DP cells. When DPs cannot receive BMP signals, they lose signature characteristics in vitro and fail to generate HFs when engrafted with epithelial stem cells in vivo. These results reveal that BMP signaling, in addition to its key role in epithelial stem cell maintenance and progenitor cell differentiation, is essential for DP cell function, and suggest that it is a critical feature of the complex epithelial-mesenchymal cross-talk necessary to make hair.
PMID:
18281466
[PubMed – indexed for MEDLINE] Cell. 2004 Mar 19;116(6):769-78.
Socializing with the neighbors: stem cells and their niche.
Fuchs E, Tumbar T, Guasch G.
Source
Howard Hughes Medical Institute, The Rockefeller University, New York, NY 10021, USA. fuchslb@rockefeller.edu
Abstract
The potential of stem cells in regenerative medicine relies upon removing them from their natural habitat, propagating them in culture, and placing them into a foreign tissue environment. To do so, it is essential to understand how stem cells interact with their microenvironment, the so-called stem cell niche, to establish and maintain their properties. In this review, we examine adult stem cell niches and their impact on stem cell biology.
PMID:
15035980
[PubMed – indexed for MEDLINE] Exp Gerontol. 2008 Nov;43(11):986-97. Epub 2008 Sep 9.
Human skin stem cells and the ageing process.
Zouboulis CC, Adjaye J, Akamatsu H, Moe-Behrens G, Niemann C.
Source
Department of Dermatology, Venereology, Allergology and Immunology, Dessau Medical Center, Dessau, Germany. christos.zouboulis@klinikum-dessau.de
Abstract
In healthy individuals, skin integrity is maintained by epidermal stem cells which self-renew and generate daughter cells that undergo terminal differentiation. Despite accumulation of senescence markers in aged skin, epidermal stem cells are maintained at normal levels throughout life. Therefore, skin ageing is induced by impaired stem cell mobilisation or reduced number of stem cells able to respond to proliferative signals. In the skin, existence of several distinct stem cell populations has been reported. Genetic labelling studies detected multipotent stem cells of the hair follicle bulge to support regeneration of hair follicles but not been responsible for maintaining interfollicular epidermis, which exhibits a distinct stem cell population. Hair follicle epithelial stem cells have at least a dual function: hair follicle remodelling in daily life and epidermal regeneration whenever skin integrity is severely compromised, e.g. after burns. Bulge cells, the first adult stem cells of the hair follicle been identified, are capable of forming hair follicles, interfollicular epidermis and sebaceous glands. In addition, — at least in murine hair follicles — they can also give rise to non-epithelial cells, indicating a lineage-independent pluripotent character. Multipotent cells (skin-derived precursor cells) are present in human dermis; dermal stem cells represent 0.3% among human dermal foreskin fibroblasts. A resident pool of progenitor cells exists within the sebaceous gland, which is able to differentiate into both sebocytes and interfollicular epidermis. The self-renewal and multi-lineage differentiation of skin stem cells make these cells attractive for ageing process studies but also for regenerative medicine, tissue repair, gene therapy and cell-based therapy with autologous adult stem cells not only in dermatology. In addition, they provide in vitro models to study epidermal lineage selection and its role in the ageing process.

Exp Gerontol. 2008 Nov;43(11):986-97. Epub 2008 Sep 9.
Human skin stem cells and the ageing process.
Zouboulis CC, Adjaye J, Akamatsu H, Moe-Behrens G, Niemann C.
Source
Department of Dermatology, Venereology, Allergology and Immunology, Dessau Medical Center, Dessau, Germany. christos.zouboulis@klinikum-dessau.de
Abstract
In healthy individuals, skin integrity is maintained by epidermal stem cells which self-renew and generate daughter cells that undergo terminal differentiation. Despite accumulation of senescence markers in aged skin, epidermal stem cells are maintained at normal levels throughout life. Therefore, skin ageing is induced by impaired stem cell mobilisation or reduced number of stem cells able to respond to proliferative signals. In the skin, existence of several distinct stem cell populations has been reported. Genetic labelling studies detected multipotent stem cells of the hair follicle bulge to support regeneration of hair follicles but not been responsible for maintaining interfollicular epidermis, which exhibits a distinct stem cell population. Hair follicle epithelial stem cells have at least a dual function: hair follicle remodelling in daily life and epidermal regeneration whenever skin integrity is severely compromised, e.g. after burns. Bulge cells, the first adult stem cells of the hair follicle been identified, are capable of forming hair follicles, interfollicular epidermis and sebaceous glands. In addition, — at least in murine hair follicles — they can also give rise to non-epithelial cells, indicating a lineage-independent pluripotent character. Multipotent cells (skin-derived precursor cells) are present in human dermis; dermal stem cells represent 0.3% among human dermal foreskin fibroblasts. A resident pool of progenitor cells exists within the sebaceous gland, which is able to differentiate into both sebocytes and interfollicular epidermis. The self-renewal and multi-lineage differentiation of skin stem cells make these cells attractive for ageing process studies but also for regenerative medicine, tissue repair, gene therapy and cell-based therapy with autologous adult stem cells not only in dermatology. In addition, they provide in vitro models to study epidermal lineage selection and its role in the ageing process.

J Clin Invest. 2011 Feb 1;121(2):613-22. doi: 10.1172/JCI44478. Epub 2011 Jan 4.
Bald scalp in men with androgenetic alopecia retains hair follicle stem cells but lacks CD200-rich and CD34-positive hair follicle progenitor cells.
Garza LA, Yang CC, Zhao T, Blatt HB, Lee M, He H, Stanton DC, Carrasco L, Spiegel JH, Tobias JW, Cotsarelis G.
Source
Department of Dermatology, Kligman Laboratories, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.
Abstract
Androgenetic alopecia (AGA), also known as common baldness, is characterized by a marked decrease in hair follicle size, which could be related to the loss of hair follicle stem or progenitor cells. To test this hypothesis, we analyzed bald and non-bald scalp from AGA individuals for the presence of hair follicle stem and progenitor cells. Cells expressing cytokeratin15 (KRT15), CD200, CD34, and integrin, α6 (ITGA6) were quantitated via flow cytometry. High levels of KRT15 expression correlated with stem cell properties of small cell size and quiescence. These KRT15(hi) stem cells were maintained in bald scalp samples. However, CD200(hi)ITGA6(hi) and CD34(hi) cell populations–which both possessed a progenitor phenotype, in that they localized closely to the stem cell-rich bulge area but were larger and more proliferative than the KRT15(hi) stem cells–were markedly diminished. In functional assays, analogous CD200(hi)Itga6(hi) cells from murine hair follicles were multipotent and generated new hair follicles in skin reconstitution assays. These findings support the notion that a defect in conversion of hair follicle stem cells to progenitor cells plays a role in the pathogenesis of AGA.
PMID:
21206086
[PubMed – indexed for MEDLINE] PMCID: PMC3026732

J Dermatol Sci. 2010 Jan;57(1):2-11.
Review of hair follicle dermal cells.
Yang CC, Cotsarelis G.
Source
Department of Dermatology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
Abstract
Hair follicle stem cells in the epithelial bulge are responsible for the continual regeneration of the hair follicle during cycling. The bulge cells reside in a niche composed of dermal cells. The dermal compartment of the hair follicle consists of the dermal papilla and dermal sheath. Interactions between hair follicle epithelial and dermal cells are necessary for hair follicle morphogenesis during development and in hair reconstitution assays. Dermal papilla and dermal sheath cells express specific markers and possess distinctive morphology and behavior in culture. These cells can induce hair follicle differentiation in epithelial cells and are required in hair reconstitution assays either in the form of intact tissue, dissociated freshly prepared cells or cultured cells. This review will focus on hair follicle dermal cells since most therapeutic efforts to date have concentrated on this aspect of the hair follicle, with the idea that enriching hair-inductive dermal cell populations and expanding their number by culture while maintaining their properties, will establish an efficient hair reconstitution assay that could eventually have therapeutic implications.
Copyright 2009 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.

Biochemistry (Mosc). 2004 Jan;69(1):81-90.
Photobiological principles of therapeutic applications of laser radiation.
Vladimirov YA, Osipov AN, Klebanov GI.
Source
Department of Biophysics, Russian State Medical University, Moscow, 117513, Russia. yuvlad@newmail.ru
Abstract
Laser therapy based on the stimulating and healing action of light of low-intensity lasers (LIL), along with laser surgery and photodynamic therapy, has been lately widely applied in the irradiation of human tissues in the absence of exogenous photosensitizers. Besides LIL, light-emitting diodes are used in phototherapy (photobiostimulation) whose action, like that of LIL, depends on the radiation wavelength, dose, and distribution of light intensity in time but, according to all available data, does not depend on the coherence of radiation.

Effects of combined mesenchymal stem cells and heme oxygenase-1 therapy on cardiac performance.
Zeng B, Chen H, Zhu C, Ren X, Lin G, Cao F.
Source
Department of Cardiology, Renmin Hospital of Wuhan University, 238 Jiefang Road, Wuhan, Hubei, PR China. zengbin19982005@yahoo.com.cn
Abstract
OBJECTIVE:
Bone marrow mesenchymal stem cells (MSCs) have the potential to repair the infarcted myocardium and improve cardiac function. However, this approach is limited by its poor viability after transplantation, and controversy still exists over the mechanism by which MSCs contribute to the tissue repair.
METHODS:
The human heme oxygenase-1 (hHO-1) was transfected into cultured MSCs using an adenoviral vector. 1 x 10(6) Ad-hHO-1-transfected MSCs (HO-1-MSCs) or Ad-Null-transfected MSCs (Null-MSCs) or PBS only (PBS group) were injected intramyocardially into rat hearts 1h after myocardial infarction.
RESULTS:
HO-1-MSCs survived in the infarcted myocardium, and expressed hHO-1 mRNA. The expression of basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) was significantly enhanced in HO-1-MSCs-treated hearts. At the same time, there were significant reduction of TNF-alpha, IL-1-beta and IL-6 mRNA, and marked increase of IL-10 mRNA in HO-1-MSCs-treated hearts. Moreover, a further downregulation of proapoptotic protein, Bax, and a marked increase in microvessel density were observed in HO-1-MSCs-treated hearts. The infarct size and cardiac performance were also significantly improved in HO-1-MSCs-treated hearts.
CONCLUSION:
The combined approach improves MSCs survival and is superior to MSCs injection alone.
PMID:
18640847
[PubMed – indexed for MEDLINE]

Conf Proc IEEE Eng Med Biol Soc. 2007;2007:5830-33.
Effects of low level red-light irradiation on the proliferation of mesenchymal stem cells derived from rat bone marrow.
Li WT, Leu YC.
Source
Department of Biomedical Engineering, Chung-Yuan Christian University, Chung-Li, 32023 Taiwan, ROC. wtli@be.cycu.edu.tw
Abstract
Mesenchymal stem cells (MSCs) are capable of regenerating various mesenchymal tissues and are essential in supporting the growth and differentiation of hematopoietic stem cells within the bone marrow microenvironment in vivo. To achieve clinically meaningful numbers of cells, many approaches have been used to maintain the differentiation potentialities and expand enough cells for clinical treatments. Previously, we have reported that low level light irradiation (LLLI) using 630 nm light emitting diodes (LEDs) could enhance replicative and colony formation potentials of MSCs derived from human bone marrow. The purpose was to study the effect on the proliferation of MSCs derived from the rat bone marrow by red light LLLI (630 nm) under different parameters of irradiation. The irradiance used was 5, 10 or 15 mW/cm2, and the radiant exposure was 2 or 4 J/cm2. Rat MSCs were irradiated at room temperature with single and multiple exposures. The results showed that the proliferation of MSCs plated at the low density (100 cells/well) and high density (1000 cells/well) was enhanced by multiple exposures of red-light LED treatment. The rate of proliferation of MSCs plated at the high density was not as high as those plated at the low density. The optimal parameter for LLLI was at irradiance of 15 mW/cm2, and radiant exposure of 4 J/cm2. The effect on the proliferation of cells by single dose irradiation was temporary. Multiple stimuli may be necessary for the enhancement of cell growth.
PMID:
18003339
[PubMed – indexed for MEDLINE]

Lasers Surg Med. 2007 Apr;39(4):373-8.
Low-level laser irradiation (LLLI) promotes proliferation of mesenchymal and cardiac stem cells in culture.
Tuby H, Maltz L, Oron U.
Source
Department of Zoology, The George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv 69978, Israel.
Abstract
BACKGROUND AND OBJECTIVES:
Low-level laser irradiation (LLLI) was found to promote the proliferation of various types of cells in vitro. Stem cells in general are of significance for implantation in regenerative medicine. The aim of the present study was to investigate the effect of LLLI on the proliferation of mesenchymal stem cells (MSCs) and cardiac stem cells (CSCs).
STUDY DESIGN/MATERIALS AND METHODS:
Isolation of MSCs and CSCs was performed. The cells were cultured and laser irradiation was applied at energy densities of 1 and 3 J/cm2.
RESULTS:
The number of MSCs and CSCs up to 2 and 4 weeks respectively, post-LLLI demonstrated a significant increase in the laser-treated cultures as compared to the control.
CONCLUSION:
The present study clearly demonstrates the ability of LLLI to promote proliferation of MSCs and CSCs in vitro. These results may have an important impact on regenerative medicine.
(c) 2007 Wiley-Liss, Inc.
PMID:
17457844
[PubMed – indexed for MEDLINE]

Lasers Med Sci. 2010 Jan;25(1):33-9. Epub 2009 Jan 27.
Effect of low-level laser irradiation and epidermal growth factor on adult human adipose-derived stem cells.
Mvula B, Moore TJ, Abrahamse H.
Source
Laser Research Group, Faculty of Health Science, University of Johannesburg, Doornfontein, Johannesburg, 2028, South Africa.
Abstract
The study investigated the effects of low-level laser radiation and epidermal growth factor (EGF) on adult adipose-derived stem cells (ADSCs) isolated from human adipose tissue. Isolated cells were cultured to semi-confluence, and the monolayers of ADSCs were exposed to low-level laser at 5 J/cm(2) using 636 nm diode laser. Cell viability and proliferation were monitored using adenosine triphosphate (ATP) luminescence and optical density at 0 h, 24 h and 48 h after irradiation. Application of low-level laser irradiation at 5 J/cm(2) on human ADSCs cultured with EGF increased the viability and proliferation of these cells. The results indicate that low-level laser irradiation in combination with EGF enhances the proliferation and maintenance of ADSCs in vitro.
PMID:
19172344
[PubMed – indexed for MEDLINE]

Lasers Med Sci. 2008 Jul;23(3):277-82. Epub 2007 Aug 23.
The effect of low level laser irradiation on adult human adipose derived stem cells.
Mvula B, Mathope T, Moore T, Abrahamse H.
Source
Laser Research Group, Faculty of Health Sciences, University of Johannesburg, PO Box 17011, Doornfontein, Johannesburg, South Africa.
Abstract
This study investigated the effect of low level laser irradiation on primary cultures of adult human adipose derived stem cells (ADSC) using a 635-nm diode laser, at 5 J/cm(2) with a power output of 50.2 mW and a power density of 5.5 mW/cm(2). Cellular morphology did not appear to change after irradiation. Using the trypan blue exclusion test, the cellular viability of irradiated cells increased by 1% at 24 h and 1.6% at 48 h but was not statistically significant. However, the increase of cellular viability as measured by ATP luminescence was statistically significant at 48 h (p < 0.05). Proliferation of irradiated cells, measured by optical density, resulted in statistically significant increases in values compared to nonirradiated cells (p < 0.05) at both time points. Western blot analysis and immunocytochemical labeling indicated an increase in the expression of stem cell marker beta1-integrin after irradiation. These results indicate that 5 J/cm(2) of laser irradiation can positively affect human adipose stem cells by increasing cellular viability, proliferation, and expression of beta1-integrin.
PMID:
17713825
[PubMed – indexed for MEDLINE]