Differentiation of Human Dermal Fibroblasts and Applications in Tissue Engineering
Total Page:16
File Type:pdf, Size:1020Kb
LINKÖPING UNIVERSITY MEDICAL DISSERTATIONS NO. 1202 DIFFERENTIATION OF HUMAN DERMAL FIBROBLASTS AND APPLICATIONS IN TISSUE ENGINEERING Pehr Sommar Division of Surgery Department of Clinical and Experimental Medicine Faculty of Health Sciences SE-581 85 Linköping, Sweden 2010 Published papers are reprinted with permission from the publisher. Printed by LiU-Tryck, Linköping, Sweden, 2010 © Pehr Sommar Cover by Pehr Sommar and Johan PE Junker Photos by Pehr Sommar, Figure 5; Sofia Pettersson Illustrations by Pehr Sommar and Kalle Lundgren ISBN 978-91-7393-326-1 ISSN 0345-0082 To Marie and Ingrid SUPERVISOR Gunnar Kratz, Professor Laboratory for Reconstructive Plastic Surgery Department of Plastic Surgery, Hand Surgery and Burns Department of Clinical and Experimental Medicine Linköping University, Sweden CO-SUPERVISOR Thomas Hansson, MD, PhD Department of Plastic Surgery, Hand Surgery and Burns University Hospital, Linköping, Sweden OPPONENT Anders Lindahl, Professor Institute of Biomedicine Department of Clinical Chemistry and Transfusion Medicine Sahlgrenska University Hospital, Gothenburg, Sweden COMMITTEE BOARD Sven Hammarström, Professor Division of Cell Biology Department of Clinical and Experimental Medicine Linköping University, Sweden Per Wretenberg, MD, PhD Department of Molecular Medicine and Surgery Section of Orthopaedics and Sports Medicine Karolinska Institute Karolinska University Hospital, Stockholm, Sweden Avni Abdiu, MD, PhD Department of Plastic Surgery, Hand Surgery and Burns University Hospital, Linköping, Sweden ABSTRACT Tissue engineering applies principles of biology and engineering to the development of functional substitutes for damaged or lost tissues. Tools for the neo-generation of tissue in tissue engineering research include cells, biomaterials and soluble factors. One main obstacle in tissue engineering is the limited availability of autologous tissue specific progenitor cells. This has led to interest into using autologous cells with stem cell plasticity. Bone marrow derived stem cells were the first adult stem cells shown to have multilineage potential. Since, several reports have been published indicating that cells from other tissues; fat, muscle, connective tissue e.g., possess potential to differentiate into lineages distinct from their tissue of origin. The optimal cell type for use in tissue engineering applications should be easy to obtain, cultivate and store. The human dermal fibroblast is an easily accessible cell source, which after routine cell expansion gives a substantial cell yield from a small skin biopsy. Hence, the dermal fibroblast could be a suitable cell source for tissue engineering applications. The main aim of this thesis was to investigate the differentiation capacity of human dermal fibroblasts, and their possible applications in bone and cartilage tissue engineering applications. Human dermal fibroblasts were shown to differentiate towards adipogenic, chondrogenic, and osteogenic phenotypes upon subjection to specific induction media. Differentiation was seen both in unrefined primary cultures and in clonal populations (paper I). Fibroblasts could be used to create three-dimensional cartilage- and bone like tissue when grown in vitro on gelatin microcarriers in combination with platelet rich plasma (paper II). 4 weeks after in vivo implantation of osteogenic induced fibroblasts into a fracture model in athymic rats, dense cell clusters and viable human cells were found in the gaps, but no visible healing of defects as determined by CT-scanning (paper III). After the induction towards adipogenic, chondrogenic, endotheliogenic and osteogenic lineages, gene expression analysis by microarray and quantitative real-time-PCR found several master regulatory genes important for lineage commitment, as well as phenotypically relevant genes regulated as compared to reference cultures (paper IV). In conclusion, results obtained in this thesis suggest an inherent ability for controllable phenotype alteration of human dermal fibroblasts in vitro. We conclude that dermal fibroblasts could be induced towards adipogenic, chondrogenic, endotheliogenic or osteogenic novel phenotypes, which suggest a genetic readiness of differentiated fibroblasts for lineage- specific biological functionality, indicating that human dermal fibroblasts might be a suitable cell source in tissue engineering applications. TABLE OF CONTENTS INTRODUCTION ................................................................................................................................................. 1 TISSUE ENGINEERING................................................................................................................................... 1 CELLS IN TISSUE ENGINEERING ................................................................................................................. 1 Stem cells and cellular differentiation ........................................................................................................... 2 Embryonic stem cells (ESCs) ......................................................................................................................... 3 Adult stem cells (ASCs).................................................................................................................................. 4 Induced pluripotent stem cells (iPSCs) .......................................................................................................... 5 Dermal fibroblasts ......................................................................................................................................... 6 BIOMATERIALS .............................................................................................................................................. 7 SOLUBLE FACTORS ....................................................................................................................................... 8 TISSUE ENGINEERING APPLICATIONS ..................................................................................................... 8 Tissue engineering of cartilage ..................................................................................................................... 8 Tissue engineering of bone ............................................................................................................................ 9 Clinical applications of tissue engineering ................................................................................................. 10 ADIPOSE TISSUE ........................................................................................................................................... 11 Histological and physiological features of adipose tissue ........................................................................... 11 Regulators of adipogenesis .......................................................................................................................... 11 Adipogenic induction factors ....................................................................................................................... 12 CARTILAGE TISSUE ..................................................................................................................................... 13 Histological and molecular features of cartilage ........................................................................................ 13 Regulators of chondrogenesis ..................................................................................................................... 15 Chondrogenic induction factors .................................................................................................................. 16 BONE TISSUE ................................................................................................................................................. 17 Histological and physiological features of bone ......................................................................................... 17 Regulators of osteogenesis .......................................................................................................................... 18 Osteogenic induction factors ....................................................................................................................... 19 ENDOTHELIAL CELLS ................................................................................................................................. 20 Histological and physiological features of the endothelium ........................................................................ 20 Regulators of endotheliogenesis .................................................................................................................. 21 Endothelial induction factors ...................................................................................................................... 22 AIMS .................................................................................................................................................................... 23 MATERIALS AND METHODS ....................................................................................................................... 25 ETHICAL PERMISSION ................................................................................................................................ 25 CELL HARVEST AND INDUCTION ............................................................................................................ 25 Fibroblasts ..................................................................................................................................................