COLLAGEN IN SITU GROWN CALCIUM PHOSPHATE SCAFFOLDS
FOR OSTEOGENIC DIFFERENTIATION OF WHARTON&rsquo / S JELLY AND
MENSTRUAL BLOOD STEM CELLS
Karadas, Ö / zge
M.Sc., Department of Biotechnology
Supervisor : Prof. Dr. Vasif Hasirci
Co-Supervisor: Assoc. Prof. Dr. Gamze Torun Kö / se
February 2011, 91 pages
The importance of developing new techniques for the treatment of bone
and joint diseases is increasing continuosly together with the increase of human
population and the average life span. Especially bone fractures as a result of
osteoporosis are often seen in humans older than 50 years old. The expenses of
bone and joint disease operations are very high and the duration of recovery is
long. Because of these reasons World Health Organization, The United Nations
and 37 countries announced that the years 2000-2010 is the Bone and Joint
Decade. Tissue engineering is an alternative approach to clinically applied
methods. In this study collagen scaffolds crosslinked with genipin, to improve the
stability of foams in culture media, were prepared by lyophilization. To mimic the
natural bone structure calcium phosphate mineral phase in the foam was formed
by wet chemical precipitation. Collagen concentration (0.75% and 1%, w/v),
freezing temperature (-20 oC and -80 oC) of the collagen solution before
lyophilization and immersion duration (2x4 h and 2x48 h) of the foams in calcium
and phosphate solutions for wet chemical precipitation were changed as process
v
parameters of foam production. Pore size distribution and porosity analysis as
well as compression test were performed for characterization of the scaffolds. The
foam with 1% w/v collagen concentration, frozen at -20 oC before lyophilization
and immersed for 2x4 h in calcium and phosphate solution was chosen for in vitro
cell culture studies. The defined foam had 70% porosity and pore sizes varying
between 50 and 200 &mu / m. The elastic modulus and compressive strength of the
foam was calculated as 127.1 kPa and 234.5 kPa, respectively.
Stem cells isolated from Wharton&rsquo / s jelly (WJ) and menstrual blood (MB)
were seeded to foams to compare their osteogenic differentiation. Both cells are
isolated from discarded tissues and used in this study as an alternative to the
commonly used cells which are isolated by invasive techniques such as bone
marrow stem cells. Cells were seeded to collagen foams with and without calcium
phosphate (CaP). It was observed that WJ cells proliferated during 21 days on
collagen foams without CaP, but MB cell number decreased after day 14.
Collagen foams with CaP supported the alkaline phosphate (ALP) activity
compared to tissue culture polystyrene (TCPS) and foams without CaP. Contrarily
lower cell numbers achieved on CaP containing collagen foams, possibly because
of the calcium and phosphate concentration changes in the medium and as the
result of osteogenic differentiation. ALP activity of both cell types increased
almost 10 times and specific ALP activity (activity per cell) increased 40 times
and 150 times for WJ and MB cells, respectively on the CaP containing foams
compared to TCPS.
Therefore, in this study it was shown that in situ CaP formed collagen
foams induce osteogenic differentiation of WJ and MB cells, and these cells
isolated from discarded tissues can be used as alternative cell sources in bone
tissue engineering applications.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/12612975/index.pdf |
| Date | 01 February 2011 |
| Creators | Karadas, Ozge |
| Contributors | Hasirci, Vasif |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
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