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Fibroblast Differentiation and Models of Human Skin
Linköping University, Department of Clinical and Experimental Medicine, Division of Clinical Sciences. Linköping University, Faculty of Medicine and Health Sciences.
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis combines three publications and one manuscript, covering two principal topics: functional differentiation of human fibroblasts and laboratory models of human skin. The two topics favourably unite in the realm of tissue engineering. This thesis is therefore split into three main parts: 1. a discussion of phenotypic plasticity as it pertains to fibroblasts and the stem cell continuum; 2. a short review of engineered tissue, with particular focus on soluble factors and materials; and, 3. a motivated review of the biology, diversity and culture of skin, including skin construction.

The intended goal of our research endeavor was to achieve the  formulation of a bioactive therapy for skin regeneration. The main hypothesis was that fibroblast-to-keratinocyte differentiation would facilitate wound healing, and that the protocol for such a method could be adapted to clinical translation. The foundation for the hypothesis lay in the differentiation capabilities of primary dermal fibroblasts (Paper I). However, the goal has not yet been achieved. Instead, intermediate work on the construction of skin for the purpose of creating a model test-bed has resulted in two other publications. The use of excised human skin, a formidable reference sample for tissue engineered skin, has been used to investigate a gelatinbased material in re-epithelialization (Paper II). A first attempt at standardizing a constructed skin model also resulted in a publication: an evaluation of melanocyte influences on keratinocyte-mediated contraction (Paper III).

The introduction of melanocytes into a skin model raised questions about other appendages of the integumentary system. Our previous experience with preadipocyte isolation and identification, and our attempts at constructing three-dimensional adipose tissue, motivated further investigations into fibroblast-to-adipocyte differentiation. We investigated the possibility of activating thermogenesis in fibroblasts, a property otherwise reserved for cells of the adipogenic and myogenic lineages. Our attempts were successful, and are presently in manuscript form (Paper IV). Some further experiments and optimizations are necessary before establishing a reproducible protocol for thermogenic induction.

The knowledge obtained through these scientific inquiries have moved us closer to achieving our goals, but methodological advances are still necessary. In the meantime, we have new test-beds for investigating different interactions in skin, and that enables many new questions to be asked and answered.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2016. , 188 p.
Linköping University Medical Dissertations, ISSN 0345-0082 ; 1506
National Category
Cell Biology Medical Biotechnology
URN: urn:nbn:se:liu:diva-125925DOI: 10.3384/diss.diva-125925ISBN: 978-91-7685-849-3 (Print)OAI: diva2:910399
Public defence
2016-04-08, Hasselquistsalen, ingång 76 pl 9, Campus US, Linköping, 13:00 (Swedish)
Available from: 2016-03-09 Created: 2016-03-09 Last updated: 2016-04-12Bibliographically approved
List of papers
1. Interpreted gene expression of human dermal fibroblasts after adipo-, chondro- and osteogenic phenotype shifts
Open this publication in new window or tab >>Interpreted gene expression of human dermal fibroblasts after adipo-, chondro- and osteogenic phenotype shifts
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2012 (English)In: Differentiation, ISSN 0301-4681, E-ISSN 1432-0436, Vol. 84, no 4, 305-313 p.Article in journal (Refereed) Published
Abstract [en]

Autologous cell-based therapies promise important developments for reconstructive surgery. In vitro expansion as well as differentiation strategies could provide a substantial benefit to cellular therapies. Human dermal fibroblasts, considered ubiquitous connective tissue cells, can be coaxed towards different cellular fates, are readily available and may altogether be a suitable cell source for tissue engineering strategies. Global gene expression analysis was performed to investigate the changes of the fibroblast phenotype after four-week inductions toward adipocytic, osteoblastic and chondrocytic lineages. Differential gene regulation, interpreted through Gene Set Enrichment Analysis, highlight important similarities and differences of induced fibroblasts compared to control cultures of human fibroblasts, adipocytes, osteoblasts and articular chondrocytes. Fibroblasts show an inherent degree of phenotype plasticity that can be controlled to obtain cells supportive of multiple tissue types.

Place, publisher, year, edition, pages
Wiley-Blackwell / Elsevier, 2012
Fibroblasts, Phenotype, Plasticity, Media induction, Differentiation
National Category
Medical and Health Sciences
urn:nbn:se:liu:diva-86119 (URN)10.1016/j.diff.2012.08.003 (DOI)000310572700003 ()
Available from: 2012-12-07 Created: 2012-12-07 Last updated: 2016-03-09
2. Biodegradable Gelatin Microcarriers Facilitate Re-Epithelialization of Human Cutaneous Wounds - An In Vitro Study in Human Skin
Open this publication in new window or tab >>Biodegradable Gelatin Microcarriers Facilitate Re-Epithelialization of Human Cutaneous Wounds - An In Vitro Study in Human Skin
2015 (English)In: PLoS ONE, ISSN 1932-6203, Vol. 10, no 6, e0128093- p.Article in journal (Refereed) Published
Abstract [en]

The possibility to use a suspended tridimensional matrix as scaffolding for re-epithelialization of in vitro cutaneous wounds was investigated with the aid of a human in vitro wound healing model based on viable full thickness skin. Macroporous gelatin microcarriers, CultiSpher-S, were applied to in vitro wounds and cultured for 21 days. Tissue sections showed incorporation of wound edge keratinocytes into the microcarriers and thicker neoepidermis in wounds treated with microcarriers. Thickness of the neoepidermis was measured digitally, using immunohistochemical staining of keratins as epithelial demarcation. Air-lifting of wounds enhanced stratification in control wounds as well as wounds with CultiSpher-S. Immunohistochemical staining revealed expression of keratin 5, keratin 10, and laminin 5 in the neoepidermal component. We conclude that the CultiSpher-S microcarriers can function as tissue guiding scaffold for re-epithelialization of cutaneous wounds.

Place, publisher, year, edition, pages
Public Library of Science, 2015
National Category
Clinical Medicine
urn:nbn:se:liu:diva-120232 (URN)10.1371/journal.pone.0128093 (DOI)000355979500074 ()26061630 (PubMedID)
Available from: 2015-07-21 Created: 2015-07-20 Last updated: 2016-03-09
3. Human melanocytes mitigate keratinocyte-dependent contraction in an in vitro collagen contraction assay
Open this publication in new window or tab >>Human melanocytes mitigate keratinocyte-dependent contraction in an in vitro collagen contraction assay
2015 (English)In: Burns, ISSN 0305-4179, E-ISSN 1879-1409, Vol. 41, no 5, 1035-1042 p.Article in journal (Refereed) Published
Abstract [en]

Scarring is an extensive problem in burn care, and treatment can be especially complicated in cases of hypertrophic scarring. Contraction is an important factor in scarring but the contribution of different cell types remains unclear. We have investigated the contractile behavior of keratinocytes, melanocytes and fibroblasts by using an in vitro collagen gel assay aimed at identifying a modulating role of melanocytes in keratinocyte-mediated contraction. Cells were seeded on a collagen type I gel substrate and the change in gel dimensions were measured over time. Hematoxylin and Eosin-staining and immunohistochemistry against pan-cytokeratin and microphthalmia-associated transcription factor showed that melanocytes integrated between keratinocytes and remained there throughout the experiments. Keratinocyte- and fibroblast-seeded gels contracted significantly over time, whereas melanocyte-seeded gels did not. Co-culture assays showed that melanocytes mitigate the keratinocyte-dependent contraction (significantly slower and 18-32% less). Fibroblasts augmented the contraction in most assays (approximately 6% more). Non-contact co-cultures showed some influence on the keratinocyte-dependent contraction. Results show that mechanisms attributable to melanocytes, but not fibroblasts, can mitigate keratinocyte contractile behavior. Contact-dependent mechanisms are stronger modulators than non-contact dependent mechanisms, but both modes carry significance to the contraction modulation of keratinocytes. Further investigations are required to determine the mechanisms involved and to determine the utility of melanocytes beyond hypopigmentation in improved clinical regimes of burn wounds and wound healing.

Place, publisher, year, edition, pages
Melanocytes; Keratinocytes; Contraction; Wound healing; Fibroblasts; Scars
National Category
Clinical Medicine
urn:nbn:se:liu:diva-120329 (URN)10.1016/j.burns.2014.10.034 (DOI)000357350100015 ()25466959 (PubMedID)
Available from: 2015-07-31 Created: 2015-07-31 Last updated: 2016-03-09

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