Spider silk-based gene carriers for tumor cell-specific delivery

The present study demonstrates pDNA complexes of recombinant silk proteins containing poly(L-lysine) and tumor-homing peptides (THPs), which are globular and approximately 150-250 nm in diameter, show significant enhancement of target specificity to tumor cells by additions of F3 and CGKRK THPs. We report herein the preparation and study of novel nanoscale silk-based ionic complexes containing pDNA able to home specifically to tumor cells. Particular focus was on how the THP, F3 (KDEPQRRSARLSAKPAPPKPEPKPKKAPAKK), and CGKRK, enhanced transfection specificity to tumor cells. Genetically engineered silk proteins containing both poly(L-lysine) domains to interact with pDNA and the THP to bind to specific tumor cells for target-specific pDNA delivery were prepared using Escherichia coli, followed by in vitro and in vivo transfection experiments into MDA-MB-435 melanoma cells and highly metastatic human breast tumor MDA-MB-231 cells. Non-tumorigenic MCF-10A breast epithelial cells were used as a control cell line for in vitro tumor-specific delivery studies. These results demonstrate that combination of the bioengineered silk delivery systems and THP can serve as a versatile and useful new platform for nonviral gene delivery.

Human bone marrow-derived MSCs can home to orthotopic breast cancer tumors and promote bone metastasis

American women have a nearly 25% lifetime risk of developing breast cancer, with 20% to 40% of these patients developing life-threatening metastases. More than 70% of patients presenting with metastases have skeletal involvement, which signals progression to an incurable stage. Tumor-stroma cell interactions are only superficially understood, specifically regarding the ability of stromal cells to affect metastasis. In vivo models show that exogenously supplied human bone marrow-derived stem cells (hBMSC) migrate to breast cancer tumors, but no reports have shown endogenous hBMSC migration from the bone to primary tumors. Here, we present a model of in vivo hBMSC migration from a physiologic human bone environment to human breast tumors. Furthermore, hBMSCs alter tumor growth and bone metastasis frequency. These may home to certain breast tumors based on tumor-derived TGF-β1. Moreover, at the primary tumor level, interleukin 17B (IL-17B)/IL-17BR signaling may mediate interactions between hBMSCs and breast cancer cells.

Role of Cartilage Forming Cells in Regenerative Medicine for Cartilage Repair

Currently, cartilage repair remains a major challenge for researchers and physicians due to its limited healing capacity. Cartilage regeneration requires suitable cells; these must be easily obtained and expanded, able to produce hyaline matrix with proper mechanical properties, and demonstrate sustained integration with native tissue. At present, there is a wide variety of possible cell sources for cartilage regeneration; this review explores the diversity of sources for cartilage forming cells and the distinctive characteristics, advantages, limitations, and potential applications of each cell source. We place emphasis on cell sources used for in vitro and clinical studies.

Synthetic adipose tissue models for studying mammary gland development and breast tissue engineering

The mammary gland is a dynamic organ that continually changes its architecture and function. Reciprocal interactions between epithelium and adipocyte-containing stroma exert profound effects on all stages of its development, even though the details of these events are not fully understood. To address this issue, enormous potential exists in the utilization of synthetic adipose tissue model systems to uncover the properties and functions of adipocytes in the mammary gland. The first part of this review focuses on mammary adipose tissue (or adipocyte)-related model systems developed in recent years and their utility in investigating adipose-epithelial interactions, mammary gland morphogenesis, development and tumorigenesis. The second part shifts to the field of adipose-based breast tissue engineering, focusing on how these synthetic adipose tissue models are being constructed in vitro or in vivo for regeneration of the mammary gland, and their potentials in adipose tissue engineering also are discussed.

Electrospun silk biomaterial scaffolds for regenerative medicine

Electrospinning is a versatile technique that enables the development of nanofiber-based biomaterial scaffolds. Scaffolds can be generated that are useful for tissue engineering and regenerative medicine since they mimic the nanoscale properties of certain fibrous components of the native extracellular matrix in tissues. Silk is a natural protein with excellent biocompatibility, remarkable mechanical properties as well as tailorable degradability. Integrating these protein polymer advantages with electrospinning results in scaffolds with combined biochemical, topographical and mechanical cues with versatility for a range of biomaterial, cell and tissue studies and applications. This review covers research related to electrospinning of silk, including process parameters, post treatment of the spun fibers, functionalization of nanofibers, and the potential applications for these material systems in regenerative medicine. Research challenges and future trends are also discussed.