Cell-Free Fat Extract Prevents Tail Suspension–Induced Bone Loss by Inhibiting Osteocyte Apoptosis

Enhancing high-quality fat survival: A novel strategy using cell-free fat extract

High-quality fat (HQF) improves the survival rate of fat and volumetric filling compared to traditional Coleman fat. However, this HQF strategy inevitably leads to a significant amount of unused fat being wasted. "CEFFE" (cell-free fat extract) is an acellular aqueous-phase liquid, rich in bioactive proteins. The remaining fat from preparing HQF can be further processed into CEFFE to promote the survival of HQF. HQF was obtained and the remaining fat was processed into CEFFE, then HQF was transplanted subcutaneously in nude mice. Animal studies showed that CEFFE significantly improved the survival rate of HQF. Histological analysis revealed that CEFFE improved the survival rate of HQF, by enhancing cell proliferation activity, reducing apoptosis, increasing angiogenesis, and improving the inflammatory state. Under simulated anaerobic conditions, CEFFE also improved the viability of HQF. In vitro, studies demonstrated that CEFFE enhanced the survival rate of HQF through multiple mechanisms. Transcriptomic analysis and qPCR showed that CEFFE increased the expression of angiogenesis-related genes in ADSCs while enhancing their proliferation-related gene expression and suppressing the expression of three differentiation-related genes. Moreover, functional experiments demonstrated that CEFFE-induced ADSCs exhibited stronger proliferation and adipogenic differentiation abilities. Tube formation and migration assays revealed that CEFFE promoted tube formation and migration of HUVECs, indicating its inherent pro-angiogenic properties. CEFFE facilitated the development of M0 to M2 macrophages, suggesting its role in improving the inflammatory state. This innovative clinical strategy optimizes HQF transplantation strategy, minimizing fat wastage and enhancing the efficiency of fat utilization.

Cell-free fat extract regulates oxidative stress and alleviates Th2-mediated inflammation in atopic dermatitis

Atopic dermatitis (AD) is a common inflammatory skin disease that significantly affects patients' quality of life. This study aimed to evaluate the therapeutic potential of cell-free fat extract (FE) in AD. In this study, the therapeutic effect of DNCB-induced AD mouse models was investigated. Dermatitis scores and transepidermal water loss (TEWL) were recorded to evaluate the severity of dermatitis. Histological analysis and cytokines measurement were conducted to assess the therapeutic effect. Additionally, the ability of FE to protect cells from ROS-induced damage and its ROS scavenging capacity both in vitro and in vivo were investigated. Furthermore, we performed Th1/2 cell differentiation with and without FE to elucidate the underlying therapeutic mechanism. FE reduced apoptosis and cell death of HaCat cells exposed to oxidative stress. Moreover, FE exhibited concentration-dependent antioxidant activity and scavenged ROS both in vitro and vivo. Treatment with FE alleviated AD symptoms in mice, as evidenced by improved TEWL, restored epidermis thickness, reduced mast cell infiltration, decreased DNA oxidative damage and lower inflammatory cytokines like IFN-γ, IL-4, and IL-13. FE also inhibited the differentiation of Th2 cells in vitro. Our findings indicate that FE regulates oxidative stress and mitigates Th2-mediated inflammation in atopic dermatitis by inhibiting Th2 cell differentiation, suggesting that FE has the potential as a future treatment option for AD.

Pro-vasculogenic Fibers by PDA-Mediated Surface Functionalization Using Cell-Free Fat Extract (CEFFE)

Formation of adequate vascular network within engineered three-dimensional (3D) tissue substitutes postimplantation remains a major challenge for the success of biomaterials-based tissue regeneration. To better mimic the in vivo angiogenic and vasculogenic processes, nowadays increasing attention is given to the strategy of functionalizing biomaterial scaffolds with multiple bioactive agents. Aimed at engineering electrospun biomimicking fibers with pro-vasculogenic capability, this study was proposed to functionalize electrospun fibers of polycaprolactone/gelatin (PCL/GT) by cell-free fat extract (CEFFE or FE), a newly emerging natural "cocktail" of cytokines and growth factors extracted from human adipose tissue. This was achieved by having the electrospun PCL/GT fiber surface coated with polydopamine (PDA) followed by PDA-mediated immobilization of FE to generate the pro-vasculogenic fibers of FE-PDA@PCL/GT. It was found that the PDA-coated fibrous mat of PCL/GT exhibited a high FE-loading efficiency (∼90%) and enabled the FE to be released in a highly sustained manner. The engineered FE-PDA@PCL/GT fibers possess improved cytocompatibility, as evidenced by the enhanced cellular proliferation, migration, and RNA and protein expressions (e.g., CD31, vWF, VE-cadherin) in the human umbilical vein endothelial cells (huvECs) used. Most importantly, the FE-PDA@PCL/GT fibrous scaffolds were found to enormously stimulate tube formation in vitro, microvascular development in the in ovo chick chorioallantoic membrane (CAM) assay, and vascularization of 3D construct in a rat subcutaneous embedding model. This study highlights the potential of currently engineered pro-vasculogenic fibers as a versatile platform for engineering vascularized biomaterial constructs for functional tissue regeneration.

Effects of Weight Bearing on Marrow Adipose Tissue and Trabecular Bone after Anterior Cruciate Ligament Reconstruction in the Rat Proximal Tibial Epiphysis

The effects of mechanical unloading after anterior cruciate ligament (ACL) reconstruction on bone and marrow adipose tissue (MAT) are unclear. We investigated weight bearing effects on bone and MAT after ACL reconstruction. Rats underwent unilateral knee ACL transection and reconstruction, followed by hindlimb unloading (non-weight bearing), no intervention (low-weight bearing, the hindlimb standing time ratio (STR; operated/contralateral) during treadmill locomotion ranging from 0.55 to 0.91), or sustained morphine administration (moderate-weight bearing, STR ranging from 0.80 to 0.95). Untreated rats were used as controls. At 7 or 14 days after surgery, changes in trabecular bone and MAT in the proximal tibial were assessed histologically. Histological assessments at 7 or 14 days after surgery showed that ACL reconstruction without post-operative intervention did not significantly change trabecular bone and MAT areas. Hindlimb unloading after ACL reconstruction induced MAT accumulation with adipocyte hyperplasia and hypertrophy within 14 days, but did not significantly affect trabecular bone area. Increased weight bearing through morphine administration did not affect trabecular bone and MAT parameters. Our results suggest that early weight bearing after ACL reconstruction is important in reducing MAT accumulation, and that reduction in weight bearing alone is not sufficient to induce bone loss early after ACL reconstruction.

Potential Antioxidative Activity of Homocysteine in Erythrocytes under Oxidative Stress

Homocysteine is an amino acid containing a free sulfhydryl group, making it probably contribute to the antioxidative capacity in the body. We recently found that plasma total homocysteine (total-Hcy) concentration increased with time when whole blood samples were kept at room temperature. The present study was to elucidate how increased plasma total-Hcy is produced and explore the potential physiological role of homocysteine. Erythrocytes and leukocytes were separated and incubated in vitro; the amount of total-Hcy released by these two kinds of cells was then determined by HPLC-MS. The effects of homocysteine and methionine on reactive oxygen species (ROS) production, osmotic fragility, and methemoglobin formation in erythrocytes under oxidative stress were studied. The reducing activities of homocysteine and methionine were tested by ferryl hemoglobin (Hb) decay assay. As a result, it was discovered that erythrocytes metabolized methionine to homocysteine, which was then oxidized within the cells and released to the plasma. Homocysteine and its precursor methionine could significantly decrease Rosup-induced ROS production in erythrocytes and inhibit Rosup-induced erythrocyte's osmotic fragility increase and methemoglobin formation. Homocysteine (but not methionine) was demonstrated to enhance ferryl Hb reduction. In conclusion, erythrocytes metabolize methionine to homocysteine, which contributes to the antioxidative capability under oxidative stress and might be a supplementary protective factor for erythrocytes against ROS damage.

Microgravity-Related Changes in Bone Density and Treatment Options: A Systematic Review

Space travelers are exposed to microgravity (µg), which induces enhanced bone loss compared to the age-related bone loss on Earth. Microgravity promotes an increased bone turnover, and this obstructs space exploration. This bone loss can be slowed down by exercise on treadmills or resistive apparatus. The objective of this systematic review is to provide a current overview of the state of the art of the field of bone loss in space and possible treatment options thereof. A total of 482 unique studies were searched through PubMed and Scopus, and 37 studies met the eligibility criteria. The studies showed that, despite increased bone formation during µg, the increase in bone resorption was greater. Different types of exercise and pharmacological treatments with bisphosphonates, RANKL antibody (receptor activator of nuclear factor κβ ligand antibody), proteasome inhibitor, pan-caspase inhibitor, and interleukin-6 monoclonal antibody decrease bone resorption and promote bone formation. Additionally, recombinant irisin, cell-free fat extract, cyclic mechanical stretch-treated bone mesenchymal stem cell-derived exosomes, and strontium-containing hydroxyapatite nanoparticles also show some positive effects on bone loss.

Cell-free fat extract improves ovarian function and fertility in mice with premature ovarian insufficiency

Background

Premature ovarian insufficiency (POI) is a refractory disease that seriously affects the reproductive health of women and is increasing in incidence and prevalence globally. There is enormous demand to improve fertility in women with POI, while there is still lack of effective therapeutic methods in clinic. Cell-free fat extract (CEFFE) has been reported to contain thousands of active proteins which possess the ability to promote tissue repair in other diseases. In our study, we aimed to observe the efficacy and biosecurity of CEFFE on the repair of ovarian function and fertility of mice with POI and further explore the underlying mechanism.

Methods

In vivo, POI mice model, established by cyclophosphamide (CTX, 120 mg/kg) and busulfan (BUS, 12 mg/kg), was treated with CEFFE via the tail vein every two days for 2 weeks. Then, the weight of ovaries, estrous cycle and follicle count by H&E staining were measured. The content of AMH, E₂ and FSH in serum was measured by Enzyme-linked immunosorbent assay. Fertility was evaluated by the number of oocytes retrieved, the development of embryos in vitro and the litter size. Biosecurity of parent mice and their pups were examined by body mass and visceral index. The proliferation and apoptosis of cells in ovaries were examined by immunohistochemistry and transmission electron microscopy. Furthermore, the mRNA-Seq of mouse ovarian granulosa cells was performed to explore underlying mechanism of CEFFE. In vitro, KGN cell line and human primary ovarian granulosa cells (hGCs) were treated with 250 μM CTX for 48 h with/without CEFFE. The proliferative ability of cells was detected by cell counting kit-8 assay (CCK-8) and EDU test; the apoptosis of cells was detected by TUNEL and flow cytometry.

Results

CEFFE recovered the content of AMH, E₂ and FSH in serum, increased the number of follicles and the retrieved oocytes of POI mice (P < 0.05). CEFFE contributed to the development of embryos and improved the litter size of POI mice (P < 0.05). There was no side effect of CEFFE on parent mice and their pups. CEFFE contributed to the proliferation and inhibited the apoptosis of mouse granulosa cells in ovary, as well as in human ovarian granulosa cells (including KGN cell line and hGCs) (P < 0.05).

Conclusions

The treatment of CEFFE inhibited the apoptosis of granulosa cells and contributed to the recovery of ovarian function, as well as the fertility of mice with POI.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-03012-w.