Purpose Macromolecular delivery systems have therapeutic uses because of their ability to deliver and release drugs to specific tissues. The uptake and localization of HPMA copolymers using Asp8 as the bone-targeting moiety was determined in aged, ovariectomized (ovx) rats. PGE1 was attached via a cathepsin K-sensitive linkage to HPMA copolymer–Asp8 conjugate and was tested to determine if it could promote bone formation. Materials and Methods The uptake of FITC-labeled HPMA copolymer–Asp8 conjugate (P-Asp8-FITC) on bone surfaces was compared with the mineralization marker, tetracycline. Then a targeted PGE1-HPMA copolymer conjugate (P-Asp8-FITC-PGE1) was given as a single injection and its effects on bone formation were measured 4 weeks later. Results P-Asp8-FITC preferentially deposited on resorption surfaces, unlike tetracycline. A single injection of P-Asp8-FITC-PGE1 resulted in greater indices of bone formation in aged, ovx rats. Conclusions HPMA copolymers can be targeted to bone surfaces using Asp8, with preferential uptake on resorption surfaces. Additionally, PGE1 attached to the Asp8-targeted HPMA copolymers and given by a single injection resulted in greater bone formation measured 4 weeks later. This initial in vivo study suggests that macromolecular delivery systems targeted to bone may offer some therapeutic opportunities and advantages for the treatment of skeletal diseases.

The primary conclusion of this study was that locally applied SIM-ALN-CD has the potential to prevent episodes of periodontitis bone loss.

Spermatogenesis is a highly organized process by which undifferentiated spermatogonia self‐renew and differentiate into spermatocytes and spermatids. The entire developmental process from spermatogonia to sperm occurs within the seminiferous tubules. Spermatogenesis is supported by the close interaction of germ cells with Sertoli cells. In this study, testicular tissues were collected from Hu sheep at 8 timepoints after birth: 0, 30, 90, 180, 270, 360, 540, and 720 days. Immunofluorescence staining and histological analysis were used to explore the development of male germ cells and Sertoli cells in the Hu sheep testes at these timepoints. The changes in seminiferous tubule diameter and male germ cells in the Hu sheep testes at these different developmental stages were analyzed. Then, specific molecular markers were used to study the proliferation and differentiation of spermatogonia, the timepoint of spermatocyte appearance, and the maturation and proliferation of Sertoli cells in the seminiferous tubules. Finally, the formation of the blood–testes barrier was studied using antibodies against the main components of the blood–testes barrier, β‐catenin, and ZO‐1. These findings not only increased the understanding of the development of the Hu sheep testes, but also laid a solid theoretical foundation for Hu sheep breeding.