Decellularized Adipose Tissue Hydrogel Promotes Bone Regeneration in Critical-Sized Mouse Femoral Defect Model

Abstract

Critical-sized bone defects fail to heal and often cause non-union. Standard treatments employ autologous bone grafting, which can cause donor tissue loss/pain. Although several scaffold types can enhance bone regeneration, multiple factors limit their level of success. To address this issue, this study evaluated a novel decellularized human adipose tissue (DAT) hydrogel as an alternative. In this study, DAT hydrogel alone, or in combination with adipose-derived stromal/stem cells (ASC), osteo-induced ASCs (OIASC), and hydroxyapatite were tested for their ability to mediate repair of a critical-sized (3 mm) femoral defect created in C57BL/6 mice. Micro-computed tomography results showed that all DAT hydrogel treated groups significantly enhanced bone regeneration, with OIASC + hydroxyapatite treated group displaying the most robust bone regeneration. Histological analyses revealed that all treatments resulted in significantly higher tissue areas with the relative mineralized tissue area significantly increased at 12 weeks; however, cartilaginous content was lowest among treatment groups with OIASC. Immunohistochemical analyses showed that DAT hydrogel enhanced collagen I and osteopontin expression, while the addition of OIASCs to the hydrogel reduced collagen II levels. Thus, DAT hydrogel promotes bone regeneration in a critical-sized femoral defect model that is further enhanced in the presence of OIASCs and hydroxyapatite.

The Bone Extracellular Matrix in Bone Formation and Regeneration

“…Mohiuddin et al demonstrated that a combination of decellularized adipose tissue (DAT) with adipose-derived stromal/stem cells (ASCs) is effective in the regenerative bone repair of mice critical-size femur defects. The group treated with the DAT hydrogel showed a higher deposition of OPN and collagen I as well as a higher bone area than the untreated group (Mohiuddin et al, 2019). Beyond that, porcine small intestinal submucosa (SIS) ECM was combined with true bone ceramic (TBC) and mineralized, to fabricate the tissue-derived ECM scaffold mSIS/TBC.…”

Clinical Translational Potential in Skin Wound Regeneration for Adipose-Derived, Blood-Derived, and Cellulose Materials: Cells, Exosomes, and Hydrogels

“…These methods combine biological (enzyme digestion), chemical, and physical processing steps to achieve the uniform and consistent manufacture of protein scaffolds depleted of contaminating genomic DNA and lipids. Obatala scientists, in collaboration with partners at Pennsylvania State University (PSU), Tulane University, and Western Ontario University, have developed and published on decellularized human adipose tissue-derived extracellular matrix (ECM) hydrogel, commercially termed “AdipoGel™” [ 70 , 83 , 84 , 85 , 86 ]. This hydrogel or scaffold is prepared using a combination of chemical and mechanical processing followed by protease digestion as a final modification prior to sterilization.…”

“…This hydrogel or scaffold is prepared using a combination of chemical and mechanical processing followed by protease digestion as a final modification prior to sterilization. In vitro, AdipoGel is capable of supporting adipose-derived stromal/stem cell (ASC) proliferation and adipogenic and osteogenic differentiation; in vivo, AdipoGel promotes critical-sized endochondral bone defect repair [ 83 , 84 , 85 ]. Furthermore, the decellularized adipose-derived scaffold can be chemically modified with thiol methacrylate and cross-linked to create a cytocompatible matrix that can be “tuned” to achieve biomechanical properties appropriate for the promotion of either soft or hard tissue regeneration [ 87 ].…”

“…The decellularized tissue can be prepared as a lyophilized scaffold or as a liquid hydrogel. Both forms are compatible with in vivo applications, including subcutaneous implantation, injection for soft tissue regeneration, or as a sheet for use in orthopedic repair procedures [ 70 , 83 ]. Likewise, independent studies have demonstrated that their decellularized adipose tissue scaffolds can be used to create adipose depots when implanted into nude mice [ 82 ].…”

Human Adipose-Derived Hydrogel Characterization Based on In Vitro ASC Biocompatibility and Differentiation

“…Adipose tissue was obtained from LaCell LLC under an approved IRB protocol (Western IRB Study # 1138160, Puyallup WA) with written informed consent from donors (n = 3; BMI = 24:56 ± 2:52; age = 50 ± 5:7, mean ± standard deviation) undergoing elective abdominoplasty. Pooled adipose tissue from the three donors was decellularized and converted in to a prehydrogel (50 mg/mL) using the method described previously [35]. [36].…”