Comparative Study on Acellular Dermal Graft Versus Propylene Mesh Both Either Loaded or Unloaded with BM-MSCs in Healing of Skull Bone Defect in Rats: Histological and Immunohistochemical Study

Bone defect occurs as a consequence of many conditions. Diseased bones don’t heal properly and defects in face area need proper bone reconstruction to avoid psychological and social problems. Tissue engineering is an emerging new modality of treatment. We thought to study different methods to fill skull bone defect in rats in order to find the most safe and effective method. So, this study was designed to evaluate the efficacy of acellular dermal graft (ADM) versus propylene mesh both either loaded or unloaded with bone marrow derived mesenchymal stem cells (BM-MSCs) in healing of skull bone defect of a 5 mm diameter. The study included 36 adult male Wistar albino rats that were divided into three groups according to the way of filling skull bone defect. Group I: Ia (sham control), Ib (negative control). Group II: IIa (unseeded propylene), IIb (seeded propylene) and Group III: IIIa (unseeded ADM), IIIb (seeded ADM). The trephine operation was done on the left parietal bone. Specimens were collected four weeks postoperative and processed for H&E, osteopontin immunohistochemistry and scanning electron microscope. Morphometric and statistical analysis were also performed. After studying the results of the experiment, we found that propylene mesh and ADM were suitable scaffolds that could support new bone formation in clavarial bone defect. Healing of skull bone defect was better in rats that received seeded scaffolds more than rats with unseeded scaffolds. The seeded ADM showed significant increase in bone forming activity as confirmed by histomorphometric and statistical results.

Preparation of an acellular dermal matrix using the freeze-thawing technique with and without gamma irradiation

An acellular dermal matrix [ADM] is a dermal substitute in which the skin is treated to remove epithelial and dermal cellular components. To compare the histological and immunohistochemical structures of ADMs prepared using the freeze-thawing technique with or without gamma irradiation. Twenty-one human skin specimens were used and divided into three equal groups: group I [control group], group II, in which skin specimens were subjected to three repeated freeze-thawing cycles, and group III, in which skin specimens were subjected to three repeated freeze-thawing cycles and subsequent exposure to 5000 rad gamma irradiation. Skin specimens from the previous groups were examined histologically and immunohistochemically for laminin. A morphometric study was carried out for the determination of the number of cells per high-power field [hpf] in both the papillary and the reticular dermis. Both methods of ADM preparation resulted in extensive extraction of cellular components with preservation of the basic dermal architecture as there was a highly significant decrease in the number of cells/hpf in both layers of the dermis in groups II and III as compared with the control group [P<0.001]. However, there was further decellularization in group III as there was a highly significant decrease in the number of cells/ hpf in both the papillary and the reticular dermis in group III as compared with group II [P<0.001]. Immunohistochemical stain of laminin revealed preservation of the epidermal basement membrane in groups II and III. A combination of irradiation and a freeze-thawing technique is recommended in the preparation of ADM for efficient decellularization

Relation between postmenopausal histological changes in the human iliac bone and osteoprotegerin protein expression

Postinenopausal bone resorption is influenced by a variety of factors that result in increased activation of osteoclasts. Osteoblasts were reported to secrete an osteoclast inhibiting protein named osteoprotegerin and this secretion was found to be influenced by the estrogen hormone level. So, the aim of this study was to investigate osteoprotegerin protein expression in human female bone and assess its relation to structural bone changes occurring after menopause. This study was conducted on 34 specimens from the iliac crest of female subjects undergoing bone grafts after taking their consent. They were divided into 3 groups. Females of group. I were in the premenopausal period. Those of group II were um the early postmenopausal period while those of group ill were in the late postmenopausal period. Osteoprotegerin protein expression was seen mainly in the cytoplasm of osteogenic cells and osteoblasts lining the bone trabeculae of the iliac crests. This expression was significantly higher in the premenopausal women as compared to both postmenopausal groups with no significant difference between early and late postmenopausal groups. Specimens taken from postmenopausal women showed significant decrease in the trabecular thickness together with significant increase in the trabecular separation and eroded surface. These changes were more prominent In late postmenopause. There was a significant positive correlation between osteoprotegerin expression amid serum estradiol, bone volume and trabecular thickness. Meanwhile, there was a significant negative correlation between osteoprotegerin protein expression and trabecular separation and eroded surface. It was concluded that decrement of osteoprotegerin plays an important role in the pathogenesis of postmenopausal osteoporosis and it is recommended to use osteoprotegerin in future therapeutic interventions in osteoporosis

Changes in the proliferative activity of the sigmoid colon with aging in comparison with normal mucosa bordering adenocarcinomas

Epithelial lining of the crypts of the sigmoid colon is in continuous renewal and has a high proliferative activity and it is documented that the incidence of colon cancer increases with age. Therefore, the aim of this study was to investigate the changes in the proliferative activity of the normal sigmoid colon with aging and to compare it with that of the normal mucosa taken at least 10 cms from the edge of the adenocarcinoma lesions. This is study was done on twenty human subjects that were divided into 2 group: GI aged 20-35 years aged GII aged 55-70 years. Each group was divided into 2 subgroups: subgroups A where specimens were taken from colonoscopically normal individuals that also showed no microscopic abnormalities and subgroup B where specimens were taken from normal mucosa at least 10 cms from the edge of adenocarcinoma lesions. Proliferative activity was estimated using PCNA index and the apoptotic activity was estimated by examining the anti-apoptotic Bcl-2 protein expression. Restilts showed hyperplasia in the epithelial lining of the crypts of the aged sigmoid colon. There was a highly significant increase in the PCNA index and in the anti-apoptotic Bcl-2 protein expression with aging in normal human subjects. PCNA index was significantly higher in normal mucosa of adenocarcinoma patients than in mucosa of normal individuals of the same age group. There was a significant increase in the alcian blue positive acid mucins with aging with no detectable difference between mucosa of normal individuals and normal mucosa of adenocarcinoma patients of the same age group. It was concluded that there is enhanced proliferation and decreased apoptosis in the epithelial lining of the sigmoid colon with aging and these changes may be partly responsible for the increased rate of colon cancer with aging. Also, the normal mucosa in patients with adenocarcinoma has higher proliferative and less apoptotic activities than the mucosa of normal individuals