In the organ microenvironment stromal cells make up an essential population, however research on them has been very limited. The stroma mainly consists of fibroblasts that reside together with mesenchymal cells, endothelial cells, pericytes, neurons, adipocytes, immune cells etc. The different morphologies and functional properties of stromal cells have led to subclassification of different cell types in connective tissue. Among them are the interstitial cells of Cajal and telocytes. Telocytes are one of the newer cells known for their small cell bodies and long telopods and have been recently identified in the connective tissue of many organs. Telocytes are strategically positioned near nerve endings, around blood capillaries and in close relation with particular cells. The network of telocytes is engaged in integrating information from multiple sources and coordinating the tissue homeostasis in response to the tissues local functional requirements. Extracellular vesicles provide a means of bidirectional communication, and their secretome appears to control the mechanisms of stem cell differentiation. Telocytes have been identified in various organs, specifically in human heart, lungs, brain, eye, thyroid, skeletal muscles, skin, salivary glands, gastrointestinal tract, pancreas, gallbladder, liver, and organs of the male and female urogenital system. Additionally, given the heterogeneity of the organs in which telocytes are found, and their capability to play a role in the etiopathogenesis of various diseases, the concept of "telocytopathies" has emerged. In conclusion, telocytes are increasingly becoming a focal point for the understanding of idiopathic diseases that affect humans as well as the development of new diagnostic and therapeutic approaches, and they have the potential to contribute to regenerative medicine.

Objective: The Masquelet technique is a 2-stage surgical method used for the reconstruction of critically sized bone defects due to various etiologies. Estrogen is known to have anabolic effects on bone metabolism. In this study, based on literature data, the aim is to systematically evaluate the histological and immunohistochemical effects of adding different doses of estrogen to polymethylmethacrylate cement on induced membrane tissue. Methods: Twenty-eight male rats were included in the study and divided into 4 groups. Three experimental groups received different doses of estradiol, a subtype of estrogen mixed with bone cement, while a control group received only bone cement. Approximately 10 mm defects were created in single femurs of all rats. Bone cement appropriate for each experimental group was placed in these defects, and bone fixation was performed with mini plates and screws. Tissue samples taken from all animals at the end of the sixth week were evaluated by histological and immunohistochemical methods. Results: Histological and immunohistochemical evaluations of the induced membranes obtained at the end of the experiment revealed signs of bone formation in all subgroups. A significant increase in bone formation was observed with increasing doses in groups E1, E2, and E3 compared to the control group (P < .05). The histological scores of the study groups were found to increase statistically significantly with increasing estrogen dose (P < .05). Furthermore, immunohistochemical analyses revealed that the immuno-reactive scores for bone morphogenetic protein-4 and insulin-like growth factor-1 expression were significantly higher in the E3 group compared to the other groups (P < .05). Conclusion: In this study, it was found that enriching the cement content with estrogen during bone cement placement, the first step of the Masquelet technique, improved the quality of the formed membrane. This improvement in membrane quality is promising for increasing treatment efficacy and shortening the treatment duration. Cite this article as: Çiftçi MU, Purelku M, Özönder F, et al. Dose-dependent effects of estrogen-enriched bone cement on membrane quality in the masquelet technique: experimental rat model. Acta Orthop Traumatol Turc., 2026; 60(1), 0355, doi: 10.5152/j.aott.2026.25355.