الفهرس 
AcknowledgmentOnly 14 pages are availabe for public view
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Abstract
Osteoporosis is a disease which affects a large number of population; its incidence is increasing with advancing age. The relationship of osteoporosis to alveolar bone loss has been addressed in a limited number of studies. Osteoporosis arising as a result of adverse effect for some drugs had shown a great interest to researchers nowadays to limit their side effect using natural materials such as mesenchymal stem cells and microvesicles.
The present study was conducted to investigate the healing Potential of microvesicles and mesenchymal stem cells in treating GI osteoporosis. The histological, histomorphometrical and bone mineral dentistry using DEXA scan were used to evaluate the bone regeneration.
Twenty six adult female albino rats with an average weight of 150–200g were obtained from the animal house, Faculty of Medicine were used in this study.
All rats were locally intraperitoneally injected with 200 µg/ 100 g dexamethasone in order to induce osteoporosis and random samples from each group were examined after 30 days with DEXA.
After induction of osteoporosis. The rats were randomly assigned into 2 groups. group I:
Thirteen rats received 1 million cells per rat mesenchymal stem cells in the right side (mesenchymal stem cells group) with left side positive control (osteoporosis only) which received saline injection.
group II:
Thirteen rats received 1X10(7) /ml PBS microvesicles treatment (Microvesicles group) with left side positive control (osteoporosis only) which received saline injection.
The two groups were sacrificed after another 30 days with ketamin overdose.
For comparison, additional 5 rats were used as a control group which received intraperitoneal injection of saline for 60 days and local injection at both sides of the mandible 2 times in the later 30 days.
The present investigation revealed the following results:
I) Histological results
Osteoporotic group:
This group revealed a massive bone destruction producing a reduction in bone volume. Discontinuous, irregular trabecular pattern leaving unconnected small bars dispersed in the connective tissue stroma were observed together with excessive widening and increased number of bone marrow spaces. Cellular degeneration, absences of osteoblastic lining, marked clefting of bone trabeculae with empty widened osteocytic lacunae were prominent feature of this group. Osteoclasts were hardly seen but multiple resorption pits were highly detected.
Mesenchymal stem cells group:
Following local injection of jaw with MSCs with dose of (1 million cells once per week), there was improvement in the histological picture of osteoporotic bone. New ostiod bone depositions were detected in areas facing the resorption pits. The bone marrow spaces were narrower with well-defined osteoblast lining. Newly formed bone can be detected from old bone being formed in concentric lamellae with normal mineralization filling the marrow spaces. The old bone appeared with exposed collagen fibers and empty osteocytic lacunae.
Microvesicles group:
This group showed marked improvement of bone architecture, deposition of a thick and uniformly distributed osteoid bone concomitant with a relative increase in osteocytest. Most of bone marrow spaces regained their normal size and shape with increased osteoblastic lining.
II) Histomorphometric results:
The highest mean bone area percentage was recorded in microvesicles treated group (87.612±4.385), then followed by stem cells treated group (83.140±1.108) and then normal bone (73.058 ±0.8708). The least mean bone area percentage was recorded in positive control group who received dexamethasone only (49.632±5.402). A statistically significant difference has been revealed between all groups.
III) DEXA results:
The highest mean BMD was recorded in normal bone (0.1398 ±0.001716), followed by microvesicles treated groups (0.1395 ±0.01098), then stem cells treated groups (0.1262±0.007996), t. The least mean bone mineral density was recorded in osteoporotic group (0.08938 ±0.007005). A statistically significant difference has been recorded between all groups.
IV) RANKL results:
The highest mean RANKL expression was recorded in osteoporotic group (2.56 ±0.5678). Followed by stem cells group (1.951±0.4337), Then microvesicles group (1.811±0.4336). The least RANKL expression was recorded in normal bone (0.1745±0.07115). A statistically significant difference has been recorded between all groups.