Expression of CYP1B1 but not CYP1A1 by primary cultured human mammary stromal fibroblasts constitutively and in response to dioxin exposure: role of the Ah receptor

The expression of CYP1B1 in human mammary fibroblasts (HMFs) was characterized as a potential modulator of their individual function as well as effects on adjacent mammary epithelia. We have used these characteristics to explore the diversity of fibroblast cells isolated from reduction mammoplasty patients and from different breast locations in breast cancer patients (tumors, peripheral to tumor and skin). These parameters have also been used to examine differences between two donors. The results have shown that while none of these HMFs expressed a detectable CYP1A1 protein basally or in response to TCDD, they all expressed CYP1B1 constitutively at similar levels (0.5-0.9 pmol/mg microsomal proteins) and they were induced by TCDD (up to 5-fold) consistent with mediation by the Ah receptor (AhR). DMBA metabolism by HMFs exhibited high proportions of 5,6-, 10,11- and 3,4-dihydrodiols, a profile that is typical of human CYP1B1 regioselectivity. RT-PCR followed by Southern blot analyses demonstrated that CYP1B1 mRNA expression in HMFs parallels levels of respective microsomal proteins. The AhR is expressed in these HMFs as two cytosolic forms (approximately 106 and 104 kDa) and a substantial proportion of the 104 kDa form was localized to the nucleus even prior to TCDD treatment. In all HMFs isolated directly from collagenase digested breast tissues the AhR is expressed at levels 10-fold lower than in breast epithelial cells. However, HMFs that were isolated after serial passaging of mammary epithelial cultures had shown much higher levels of the AhR expression and more dramatic TCDD-induced down-regulation (>80% in 24 h) associated with more efficient nuclear translocation. These differences suggested the presence of two functionally distinct subtypes of HMFs: interstitial stromal fibroblasts that are readily released by collagenase digestion of breast tissues, and lobular stromal fibroblasts which are more tightly associated with the breast epithelia.      

Bioengineering strategies for regeneration of craniofacial bone: a review of emerging technologies

Oral Diseases (2010) 16 , 709–716 Although advances in surgical techniques and bone grafting have significantly improved the functional and cosmetic restoration of craniofacial structures lost because of trauma or disease, there are still significant limitations in our ability to regenerate these tissues. The regeneration of oral and craniofacial tissues presents a formidable challenge that requires synthesis of basic science, clinical science, and engineering technology. Tissue engineering is an interdisciplinary field of study that addresses this challenge by applying the principles of engineering to biology and medicine toward the development of biological substitutes that restore, maintain, and improve normal function. This review will explore the impact of biomaterials design, stem cell biology and gene therapy on craniofacial tissue engineering.