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Lönnqvist, Susanna
Alternative names
Publications (10 of 13) Show all publications
Toss, H., Lönnqvist, S., Nilsson, D., Sawatdee, A., Nissa, J., Fabiano, S., . . . Simon, D. T. (2017). Ferroelectric Surfaces for Cell Release. Synthetic metals, 228, 99-104
Open this publication in new window or tab >>Ferroelectric Surfaces for Cell Release
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2017 (English)In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 228, p. 99-104Article in journal (Refereed) Published
Abstract [en]

Adherent cells cultured in vitro must usually, at some point, be detached from the culture substrate. Presently, the most common method of achieving detachment is through enzymatic treatment which breaks the adhesion points of the cells to the surface. This comes with the drawback of deteriorating the function and viability of the cells. Other methods that have previously been proposed include detachment of the cell substrate itself, which risks contaminating the cell sample, and changing the surface energy of the substrate through thermal changes, which yields low spatial resolution and risks damaging the cells if they are sensitive to temperature changes. Here cell culture substrates, based on thin films of the ferroelectric polyvinylidene fluoride trifluoroethylene (PVDF-TrFE) co-polymer, are developed for electroactive control of cell adhesion and enzyme-free detachment of cells. Fibroblasts cultured on the substrates are detached through changing the direction of polarization of the ferroelectric substrate. The method does not affect subsequent adhesion and viability of reseeded cells.

Place, publisher, year, edition, pages
Elsevier, 2017
National Category
Physical Sciences Electrical Engineering, Electronic Engineering, Information Engineering Clinical Science
Identifiers
urn:nbn:se:liu:diva-121804 (URN)10.1016/j.synthmet.2017.04.013 (DOI)000401599600015 ()
Note

Funding agencies: Swedish Governmental Agency for Innovation Systems (VINNOVA) [2010-00507]; Knut and Alice Wallenberg Foundation; Onnesjo Foundation

Available from: 2015-10-07 Created: 2015-10-07 Last updated: 2018-04-13Bibliographically approved
Lönnqvist, S. (2016). Applications of human skin in vitro. (Doctoral dissertation). Linköping: Linköping University Electronic Press
Open this publication in new window or tab >>Applications of human skin in vitro
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Chronic wounds are a substantial problem in today’s health care and place significant strains on the patient. Successful modelling of the wound healing process is pivotal for the advancement of wound treatment research. Wound healing is a dynamic and multifactorial process involving all constituents of the skin. The progression from haemostasis and inflammation to proliferation of epidermal  keratinocytes and dermal fibroblasts, and final scar maturation can be halted and result in a chronic wound that fails to re-epithelialise. The wound healing process constitutes an example of dynamic reciprocity in tissue where cellular changes take place on cues from the extracellular matrix and vice versa when tissue homeostasis is disturbed. The extracellular matrix provides a structural context for the resident cells and the epidermal keratinocytes, and a functioning interplay between the two tissue compartments is crucial for successful wound healing to take place. Work included in this thesis has applied viable human full thickness skin in vitro to investigate the re-epithelialisation process and barrier function of intact skin.The use of full thickness skin in vitro can take into account the contextual aspect of the process where the epidermal keratinocytes are activated and obtain a migratory phenotype, and are continuously dependent on the cues from the extracellular matrix and support of the dermis. When utilising skin for studies on re-epithelialisation, circular standardised full thickness wounds were created and cultured  for up to four weeks in tissue culture. In paper I, the organisation of a thick neoepidermis was investigated in the in vitro wound healing model when resident cells were provided with a porous suspended three dimensional gelatin scaffold. In paper II we investigated the use of a fluorescent staining conventionally used for proliferation studies to facilitate the tracing of transplanted epidermal cells in in vitro  wounds, in order to improve and expand the use of the model. In paper III the model was utilised to investigate the treatment approach of acidification of wounds to evaluate the suitability of such intervention in regards to keratinocyte function and re-epithelialisation. Studies on re-epithelialisation with the aid of the in vitro wound healing model provided insight in neoepidermal structure with porous gelatin scaffolding in the wound, a novel methodological approach to tracing cells and response to constrained wound healing environment. In paper IV, intact human skin was evaluated for modelling the cytotoxic response after exposure to a known irritant compound. To study barrier function, intact skin was exposed to irritants by restricting exposure topically, and full thickness skin in vitro was found suitable for modelling cytotoxicity responses. Employing human full thickness skin in vitro makes use of the actual target tissue of interest with epidermal and dermal cells, and full barrier function.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2016. p. 99
Series
Linköping University Medical Dissertations, ISSN 0345-0082 ; 1493
National Category
Clinical Medicine Clinical Science
Identifiers
urn:nbn:se:liu:diva-123313 (URN)10.3384/diss.diva-123313 (DOI)978-91-7685-895-0 (ISBN)
Public defence
2016-01-29, Berzeliussalen, Campus US, Linköping, 13:00 (English)
Opponent
Supervisors
Available from: 2015-12-10 Created: 2015-12-10 Last updated: 2015-12-18Bibliographically approved
Lönnqvist, S., Briheim, K. & Kratz, G. (2016). Non-occlusive topical exposure of human skin in vitro as model for cytotoxicity testing of irritant compounds. Toxicology Mechanisms and Methods, 26(2), 82-87
Open this publication in new window or tab >>Non-occlusive topical exposure of human skin in vitro as model for cytotoxicity testing of irritant compounds
2016 (English)In: Toxicology Mechanisms and Methods, ISSN 1537-6516, E-ISSN 1537-6524, Vol. 26, no 2, p. 82-87Article in journal (Refereed) Published
Abstract [en]

Testing of irritant compounds has traditionally been performed on animals and human volunteers. Animal testing should always be restricted and for skin irritancy mice and rabbits hold poor predictive value for irritant potential in humans. Irritant testing on human volunteers is restricted by the duration subjects can be exposed, and by the subjectivity of interpreting the visual signs of skin irritation. We propose an irritant testing system using viable human full thickness skin with the loss of cell viability in the exposed skin area as end point measurement. Skin was exposed to sodium dodecyl sulfate (SDS) at 20% concentration by non-occluded topical exposure to establish a positive control response and subsequent test compounds were statistically compared with the 20% SDS response. Cell viability and metabolism were measured with 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. The model presents correlation between increased concentration of SDS and decreased viability of cells in the exposed skin area (R2 = 0.76). We propose the model to be used for cytotoxicity testing of irritant compounds. With fully intact barrier function, the model comprises all cells present in the skin with quantifiable end point measurement.

Place, publisher, year, edition, pages
Taylor & Francis, 2016
Keywords
Human full thickness skin, in vitro model, SDS
National Category
Pharmacology and Toxicology
Identifiers
urn:nbn:se:liu:diva-123312 (URN)10.3109/15376516.2015.1091537 (DOI)000373528000002 ()26446981 (PubMedID)
Available from: 2015-12-10 Created: 2015-12-10 Last updated: 2018-01-10Bibliographically approved
Lönnqvist, S., Rakar, J., Briheim, K. & Kratz, G. (2015). Biodegradable Gelatin Microcarriers Facilitate Re-Epithelialization of Human Cutaneous Wounds - An In Vitro Study in Human Skin. PLoS ONE, 10(6), e0128093
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, E-ISSN 1932-6203, Vol. 10, no 6, p. e0128093-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
Identifiers
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: 2017-12-04
Lönnqvist, S., Emanuelsson, P. & Kratz, G. (2015). Influence of acidic pH on keratinocyte function and re-epithelialisation of human in vitro wounds. Journal of Plastic Surgery and Hand Surgery, 49(6), 346-352
Open this publication in new window or tab >>Influence of acidic pH on keratinocyte function and re-epithelialisation of human in vitro wounds
2015 (English)In: Journal of Plastic Surgery and Hand Surgery, ISSN 2000-656X, E-ISSN 2000-6764, Vol. 49, no 6, p. 346-352Article in journal (Refereed) Published
Abstract [en]

Background: Chronic wounds are one of the greatest challenges for the healthcare system. Today, a plethora of dressings are used in the treatment of these wounds, each with specific influence on the wound environment. Due to differences in the permeability of the dressings the use will result in differences in the pH balance in the wound bed. However, little is known about how changes in the pH in the wound environment affect the different phases of the healing process. Aim: The aim of the present study was to investigate the effects of acidic pH on the regeneration phase by studying keratinocyte function in vitro and re-epithelialisation in an in vitro model of human skin. Results:In vitro assays showed reduced viability and migration rates in human keratinocytes when pH was lowered. Real time PCR revealed differential expression of genes related to wound healing and environmental impairment. Tissue culture showed no re-epithelialisation of wounds subjected to pH 5.0 and moderate re-epithelialisation at pH 6.0, compared to controls at pH 7.4. Conclusion: The results indicate that lowering pH down to pH 5.0 in wounds is counterproductive in aspect of keratinocyte function which is crucial for successful wound healing.

Place, publisher, year, edition, pages
Taylor & Francis, 2015
Keywords
Keratinocyte; pH; re-epithelialisation; wound model
National Category
Clinical Medicine
Identifiers
urn:nbn:se:liu:diva-123140 (URN)10.3109/2000656X.2015.1053397 (DOI)000364409400006 ()26051107 (PubMedID)
Available from: 2015-12-07 Created: 2015-12-04 Last updated: 2017-12-01Bibliographically approved
Persson, K., Lönnqvist, S., Tybrandt, K., Gabrielsson, R., Nilsson, D., Kratz, G. & Berggren, M. (2015). Matrix Addressing of an Electronic Surface Switch Based on a Conjugated Polyelectrolyte for Cell Sorting. Advanced Functional Materials, 25(45), 7056-7063
Open this publication in new window or tab >>Matrix Addressing of an Electronic Surface Switch Based on a Conjugated Polyelectrolyte for Cell Sorting
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2015 (English)In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 25, no 45, p. 7056-7063Article in journal (Refereed) Published
Abstract [en]

Spatial control of cell detachment is potentially of great interest when selecting cells for clonal expansion and in order to obtain a homogeneous starting population of cells aimed for tissue engineering purposes. Here, selective detachment and cell sorting of human primary keratinocytes and fibroblasts is achieved using thin films of a conjugated polymer. Upon electrochemical oxidation, the polymer film swells, cracks, and finally detaches taking cells cultured on top along with it. The polymer can be patterned using standard photolithography to fabricate a cross-point matrix with polymer pixels that can be individually addressed and thus detached. Detachment occurs above a well-defined threshold of +0.7 V versus Ag/AgCl, allowing the use of a relatively simple and easily manufactured passive matrix-addressing configuration, based on a resistor network, to control the cell-sorting device.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2015
National Category
Clinical Medicine Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:liu:diva-123754 (URN)10.1002/adfm.201503542 (DOI)000366502900010 ()
Note

Funding Agencies|Swedish Foundation for Strategic Research; VINNOVA (the OBOE center) [2010-00507]; Onnesjo foundation (Holmen); Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009-00971]

Available from: 2016-01-11 Created: 2016-01-11 Last updated: 2017-11-30
Lönnqvist, S., Karlsson, M. & Kratz, G. (2015). Tracing human keratinocytes and melanocytes with carboxyfluorescein hydroxysuccinimidyl ester (CFSE) staining.
Open this publication in new window or tab >>Tracing human keratinocytes and melanocytes with carboxyfluorescein hydroxysuccinimidyl ester (CFSE) staining
2015 (English)Manuscript (preprint) (Other academic)
Abstract [en]

Burn treatment and conditions of hypopigmentation may require autologous transplantation of keratinocytes and melanocytes. The tracing of transplanted cells presents a challenge. We report a methodology based on passive staining with carboxyfluorescein hydroxysuccinimidyl ester (CFSE) that enables localising cells in tissue sections to investigate the fate of transplanted cells in wound re-epithelialisation. CFSE-stained keratinocytes and CFSE-stained melanocytes were transplanted to human full thickness in vitro wounds either as cell suspension for keratinocytes, or with the aid of  macroporous gelatin microcarriers for both cells types in single and co-culture. Viability and migration of CFSE-stained keratinocytes and melanocytes were investigated, and proliferation of the cells cultured on microcarriers was measured with flow cytometry. Wounds with transplanted cells were harvested after seven, 14 and 21 days in culture, cryosectioned and investigated using fluorescence microscopy. Sections from wounds with transplanted co-cultured keratinocytes and melanocytes were stained for pancytokeratin to distinguish double stained keratinocytes. The CFSE-staining of keratinocytes and melanocytes did not affect the viability, migration or proliferation of the cells. Transplanted cells were traced in tissue sections after 21 days and wound re-epithelialisation was not affected. We propose a novel application of CFSE-staining in transplantation studies here presented with primary human keratinocytes and melanocytes.

National Category
Clinical Medicine
Identifiers
urn:nbn:se:liu:diva-123310 (URN)
Available from: 2015-12-10 Created: 2015-12-10 Last updated: 2015-12-10Bibliographically approved
Persson, K. M., Lönnqvist, S. L., Tybrandt, K., Gabrielsson, R., Nilsson, D., Kratz, G. & Berggren, M. (2014). Selective Detachment of Human Primary Keratinocytes and Fibroblasts Using an Addressable Conjugated Polymer Matrix.
Open this publication in new window or tab >>Selective Detachment of Human Primary Keratinocytes and Fibroblasts Using an Addressable Conjugated Polymer Matrix
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2014 (English)Manuscript (preprint) (Other academic)
Abstract [en]

Conjugated polymers have been used in several applications for electronic control of cell cultures over the last years. We have shown detachment of human endothelial cells using a thin film of a self-doped water-soluble conjugated polymer. Upon electrochemical oxidation, the film swells, cracks and finally detaches taking cells cultured on top along with it. The polymer can be patterned using standard photolithography. The detachment only occurs above a threshold potential of +0.7 V and this fact has been used to create a simple actively addressed matrix, based on a resistor network placed in an encapsulated back plane. The matrix has individually detachable pixels. In this paper we have evaluated detachment of human primary keratinocytes and fibroblasts using PEDOT-S:H. In addition, we have studied effects of serum proteins, added as nutrients to the cell culture medium, on the detachment properties. It was found that at prolonged incubation times protein adhesion effectively stopped the detachment. Using shorter incubation times before detachment, both keratinocytes and fibroblasts can be detached using a regular planar device as well as the matrix device for selective detachment. Spatial control of detachment could be of use when selecting cells for clonal expansion and in order to obtain a homogeneous starting population of cells aimed for tissue engineering purposes.

National Category
Polymer Chemistry Cell Biology
Identifiers
urn:nbn:se:liu:diva-106252 (URN)
Available from: 2014-04-30 Created: 2014-04-30 Last updated: 2017-02-03Bibliographically approved
Junker, J., Lönnqvist, S., Rakar, J., Karlsson, L. K., Grenegård, M. & Kratz, G. (2013). Differentiation of human dermal fibroblasts towards endothelial cells. Differentiation, 85(3), 67-77
Open this publication in new window or tab >>Differentiation of human dermal fibroblasts towards endothelial cells
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2013 (English)In: Differentiation, ISSN 0301-4681, E-ISSN 1432-0436, Vol. 85, no 3, p. 67-77Article in journal (Refereed) Published
Abstract [en]

The ultimate goal of vascular tissue engineering is the production of functional grafts for clinical use. Difficulties acquiring autologous endothelial cells have motivated the search for alternative cell sources. Differentiation of dermal fibroblasts towards several mesenchymal lineages as well as endothelial cells has been proposed. The aim of the present study was to investigate the endothelial differentiation capacity of human dermal fibroblasts on a gene expression, protein expression and functional physiological level. Endothelial differentiation of fibroblasts was induced by culturing cells in 30% human serum, but not in fetal calf serum. Expression of proteins and genes relevant for endothelial function and differentiation was increased after induction. Furthermore, fibroblasts exposed to 30% human serum displayed increased uptake of low-density lipoprotein and formation of capillary-like networks. The results of this study may have an impact on cell sourcing for vascular tissue engineering, and the development of methods for vascularization of autologous tissue engineered constructs.

Place, publisher, year, edition, pages
Wiley-Blackwell / Elsevier, 2013
Keywords
Differentiation; Endothelial cell; Fibroblast; Tissue engineering; Human serum
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-96492 (URN)10.1016/j.diff.2013.01.005 (DOI)000320766300001 ()
Available from: 2013-08-23 Created: 2013-08-20 Last updated: 2017-12-06
Lönnqvist, S., Briheim, K. & Kratz, G. (2012). Degradable gelatin microcarriers for cell delivery to cutaneous wounds and enhanced wound healing in JOURNAL OF TISSUE ENGINEERING AND REGENERATIVE MEDICINE, vol 6, issue SI, pp 94-94. In: JOURNAL OF TISSUE ENGINEERING AND REGENERATIVE MEDICINE (pp. 94-94). John Wiley and Sons, 6(SI)
Open this publication in new window or tab >>Degradable gelatin microcarriers for cell delivery to cutaneous wounds and enhanced wound healing in JOURNAL OF TISSUE ENGINEERING AND REGENERATIVE MEDICINE, vol 6, issue SI, pp 94-94
2012 (English)In: JOURNAL OF TISSUE ENGINEERING AND REGENERATIVE MEDICINE, John Wiley and Sons , 2012, Vol. 6, no SI, p. 94-94Conference paper, Published paper (Refereed)
Abstract [en]

n/a

Place, publisher, year, edition, pages
John Wiley and Sons, 2012
Series
JOURNAL OF TISSUE ENGINEERING AND REGENERATIVE MEDICINE, ISSN 1932-6254
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-84344 (URN)000308313000340 ()
Available from: 2012-10-05 Created: 2012-10-05 Last updated: 2012-10-05
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