Sex Differences in Mesenchymal Stem Cell Therapy With Gelatin-Based Microribbon Hydrogels in a Murine Long Bone Critical-Size Defect Model

Abstract

Mesenchymal stem cell (MSC)-based therapy and novel biomaterials are promising strategies for healing of long bone critical size defects. Interleukin-4 (IL-4) over-expressing MSCs within a gelatin microribbon (µRB) scaffold was previously shown to enhance the bridging of bone within a critical size femoral bone defect in male Balb/c mice. Whether sex differences affect the healing of this bone defect in conjunction with different treatments is unknown. In this study, we generated 2-mm critical-sized femoral diaphyseal bone defects in 10–12-week-old female and male Balb/c mice. Scaffolds without cells and with unmodified MSCs were implanted immediately after the primary surgery that created the bone defect; scaffolds with IL-4 over-expressing MSCs were implanted 3 days after the primary surgery, to avoid the adverse effects of IL-4 on the initial inflammatory phase of fracture healing. Mice were euthanized 6 weeks after the primary surgery and femurs were collected. MicroCT (µCT), histochemical and immunohistochemical analyses were subsequently performed of the defect site. µRB scaffolds with IL-4 over-expressing MSCs enhanced bone healing in both female and male mice. Male mice showed higher measures of bone bridging and increased alkaline phosphatase (ALP) positive areas, total macrophages and M2 macrophages compared with female mice after receiving scaffolds with IL-4 over-expressing MSCs. Female mice showed higher Tartrate-Resistant Acid Phosphatase (TRAP) positive osteoclast numbers compared with male mice. These results demonstrated that sex differences should be considered during the application of MSC-based studies of bone healing.

Sex differences in the therapeutic effect of unaltered versus NFκB sensing IL-4 over-expressing mesenchymal stromal cells in a murine model of chronic inflammatory bone loss

“…The Wnt/β-catenin signaling pathway was significantly activated in male mice, resulting in faster fracture healing ( Haffner-Luntzer et al, 2021 ). Also, sex differences using a murine long bone critical-size defect model were compared; MSC-based therapy enhanced bone bridging with increased ALP expression especially in male mice ( Ueno et al, 2021 ). Zarei et al demonstrated sexual dimorphism with genetic and pharmacological modulation of the alternative NF-κB pathway in bone ( Zarei et al, 2019 ).…”

BMP-6 promotes type 2 immune response during enhancement of rat mandibular bone defect healing

“…Data obtained from fifty-four, 10-week-old, female, Lewis rats is reported in this study. Only female rats were used in this study as the experimental creation of atrophic nonunions is known to be reproducible only in female but not in male mice and rats (30,31). Surgical procedures and all animal care was performed in accordance with the protocols and approvals of the University of Virginia Animal Care and Use Committee.…”

Sex as a Biological Variable in Tissue Engineering and Regenerative Medicine

“…Using a hydrogel laden with interleukin (IL)-4 overexpressing mesenchymal stem cells for treating a critical-size bone defect injury in a murine model showed that healing was enhanced for both male and female mice. However, notable sex differences were observed for functional end points, such as the number of macrophages (M > F) and osteoclasts (F > M) at the site of healing (66).…”