Biological studies of distraction osteogenesis
<p xmlns:etd="http://www.ouls.ox.ac.uk/ora/modsextensions">The development of limb lengthening techniques has made possible the treatment of many congenital and acquired disorders of the adult and developing skeleton by generating new bone tissue at appropriate sites. The studies des...
| Main Authors: | , |
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| Format: | Thesis |
| Language: | English |
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1997
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| Subjects: |
| _version_ | 1797096584508342272 |
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| author | Gang., L Gang Li |
| author_facet | Gang., L Gang Li |
| author_sort | Gang., L |
| collection | OXFORD |
| description | <p xmlns:etd="http://www.ouls.ox.ac.uk/ora/modsextensions">The development of limb lengthening techniques has made possible the treatment of many congenital and acquired disorders of the adult and developing skeleton by generating new bone tissue at appropriate sites. The studies described in this thesis have attempted to elucidate some of the biological aspects of this process which is called distraction osteogenesis.</p> <p xmlns:etd="http://www.ouls.ox.ac.uk/ora/modsextensions">A rabbit model of distraction osteogenesis has been used in the present study. Lengthening at four different distraction rates (0.3, 0.7, 1.3 and 2.7 mm/day) has been investigated radiographically and histologically. The most satisfactory histology and radiology results were observed in the group distracted at a rate of 0.7 mm/day. The present study indicated that the proliferation of osteoprogenitor cells during distraction osteogenesis was affected by the rate of distraction. The rate of cell proliferation in the regenerating tissues was found to increase as the rate of lengthening increased from 0.3 to 0.7 mm/day. However, a further increase of cell proliferation did not occur at higher distraction rates.</p> <p xmlns:etd="http://www.ouls.ox.ac.uk/ora/modsextensions">In-situ hybridization techniques using non-radioactive labelling probes and imrnunohistochemistry using specific collagen antibodies have been used in the study. The localization of the mRNAs and proteins for types I and II collagen in the distraction regenerates indicates that bone is formed mainly in an intramembranous manner during distraction osteogenesis. However, higher rates of distraction resulted in increased chondrogenesis in the regenerating tissues. The osteoblasts and chondrocytes within the regenerate originate from the same pool of progenitor cells and their differentiation appeared to be altered by the rate of distraction.</p> <p xmlns:etd="http://www.ouls.ox.ac.uk/ora/modsextensions">In addition, the present study has characterized the localization of BMP-4 mRNA expression in the regenerating tissues produced by distraction osteogenesis. The BMP-4 gene was expressed mainly by less differentiated osteoprogenitor cells in the regenerating tissue, indicating that BMP-4 may play an important role in controlling the early differentiation and proliferation of osteoprogenitor cells during distraction osteogenesis.</p> <p xmlns:etd="http://www.ouls.ox.ac.uk/ora/modsextensions">The demonstration of a mixture of proliferative and apoptotic cells in the regenerating tissues, suggested that apoptosis and cell proliferation may be regulated closely during the rapid cell or tissue turnover seen in distraction osteogenesis. The changes of cells undergoing apoptosis and proliferation in the different regions of the distraction regenerate, suggested that apoptosis is an important mechanism controlling cell or tissue turnover and bone remodelling during distraction osteogenesis.</p> <p xmlns:etd="http://www.ouls.ox.ac.uk/ora/modsextensions">The neovascularization process is affected by the rate of distraction during distraction osteogenesis. A slow rate of distraction (0.3 mm/day) did not maximally stimulate angiogenesis, while the highest rate (2.7 mm/day) of distraction inhibited angiogenesis. The angiogenic response was the best at distraction rates of 0.7 and 1.3 mm/day. The clinical relevance of the present findings has been discussed and future work are suggested.</p> |
| first_indexed | 2024-03-07T04:43:56Z |
| format | Thesis |
| id | oxford-uuid:d2976713-d0f6-439a-a70c-9183d44cff81 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T04:43:56Z |
| publishDate | 1997 |
| record_format | dspace |
| spelling | oxford-uuid:d2976713-d0f6-439a-a70c-9183d44cff812022-03-27T08:05:08ZBiological studies of distraction osteogenesisThesishttp://purl.org/coar/resource_type/c_db06uuid:d2976713-d0f6-439a-a70c-9183d44cff81BonesGrowthRabbits as laboratory animalsEnglishPolonsky Theses Digitisation Project1997Gang., LGang Li<p xmlns:etd="http://www.ouls.ox.ac.uk/ora/modsextensions">The development of limb lengthening techniques has made possible the treatment of many congenital and acquired disorders of the adult and developing skeleton by generating new bone tissue at appropriate sites. The studies described in this thesis have attempted to elucidate some of the biological aspects of this process which is called distraction osteogenesis.</p> <p xmlns:etd="http://www.ouls.ox.ac.uk/ora/modsextensions">A rabbit model of distraction osteogenesis has been used in the present study. Lengthening at four different distraction rates (0.3, 0.7, 1.3 and 2.7 mm/day) has been investigated radiographically and histologically. The most satisfactory histology and radiology results were observed in the group distracted at a rate of 0.7 mm/day. The present study indicated that the proliferation of osteoprogenitor cells during distraction osteogenesis was affected by the rate of distraction. The rate of cell proliferation in the regenerating tissues was found to increase as the rate of lengthening increased from 0.3 to 0.7 mm/day. However, a further increase of cell proliferation did not occur at higher distraction rates.</p> <p xmlns:etd="http://www.ouls.ox.ac.uk/ora/modsextensions">In-situ hybridization techniques using non-radioactive labelling probes and imrnunohistochemistry using specific collagen antibodies have been used in the study. The localization of the mRNAs and proteins for types I and II collagen in the distraction regenerates indicates that bone is formed mainly in an intramembranous manner during distraction osteogenesis. However, higher rates of distraction resulted in increased chondrogenesis in the regenerating tissues. The osteoblasts and chondrocytes within the regenerate originate from the same pool of progenitor cells and their differentiation appeared to be altered by the rate of distraction.</p> <p xmlns:etd="http://www.ouls.ox.ac.uk/ora/modsextensions">In addition, the present study has characterized the localization of BMP-4 mRNA expression in the regenerating tissues produced by distraction osteogenesis. The BMP-4 gene was expressed mainly by less differentiated osteoprogenitor cells in the regenerating tissue, indicating that BMP-4 may play an important role in controlling the early differentiation and proliferation of osteoprogenitor cells during distraction osteogenesis.</p> <p xmlns:etd="http://www.ouls.ox.ac.uk/ora/modsextensions">The demonstration of a mixture of proliferative and apoptotic cells in the regenerating tissues, suggested that apoptosis and cell proliferation may be regulated closely during the rapid cell or tissue turnover seen in distraction osteogenesis. The changes of cells undergoing apoptosis and proliferation in the different regions of the distraction regenerate, suggested that apoptosis is an important mechanism controlling cell or tissue turnover and bone remodelling during distraction osteogenesis.</p> <p xmlns:etd="http://www.ouls.ox.ac.uk/ora/modsextensions">The neovascularization process is affected by the rate of distraction during distraction osteogenesis. A slow rate of distraction (0.3 mm/day) did not maximally stimulate angiogenesis, while the highest rate (2.7 mm/day) of distraction inhibited angiogenesis. The angiogenic response was the best at distraction rates of 0.7 and 1.3 mm/day. The clinical relevance of the present findings has been discussed and future work are suggested.</p> |
| spellingShingle | Bones Growth Rabbits as laboratory animals Gang., L Gang Li Biological studies of distraction osteogenesis |
| title | Biological studies of distraction osteogenesis |
| title_full | Biological studies of distraction osteogenesis |
| title_fullStr | Biological studies of distraction osteogenesis |
| title_full_unstemmed | Biological studies of distraction osteogenesis |
| title_short | Biological studies of distraction osteogenesis |
| title_sort | biological studies of distraction osteogenesis |
| topic | Bones Growth Rabbits as laboratory animals |
| work_keys_str_mv | AT gangl biologicalstudiesofdistractionosteogenesis AT gangli biologicalstudiesofdistractionosteogenesis |