Systemic DKK1 neutralization enhances human adipose-derived stem cell mediated bone repair

Abstract

Progenitor cells from adipose tissue are able to induce bone repair; however, inconsistent or unreliable efficacy has been reported across preclinical and clinical studies. Soluble inhibitory factors, such as the secreted Wnt signaling antagonists Dickkopf-1 (DKK1), are expressed to variable degrees in human adipose-derived stem cells (ASCs), and may represent a targetable "molecular brake" on ASC mediated bone repair. Here, anti-DKK1 neutralizing antibodies were observed to increase the osteogenic differentiation of human ASCs in vitro, accompanied by increased canonical Wnt signaling. Human ASCs were next engrafted into a femoral segmental bone defect in NOD-Scid mice, with animals subsequently treated with systemic anti-DKK1 or isotype control during the repair process. Human ASCs alone induced significant but modest bone repair. However, systemic anti-DKK1 induced an increase in human ASC engraftment and survival, an increase in vascular ingrowth, and ultimately improved bone repair outcomes. In summary, anti-DKK1 can be used as a method to augment cell-mediated bone regeneration, and could be particularly valuable in the contexts of impaired bone healing such as osteoporotic bone repair. K E Y W O R D S adipose stem cell, adipose stromal cell, bone healing, bone repair, bone tissue engineering, mesenchymal stem cell, Wnt signaling 1 | INTRODUCTION Nonhealing skeletal defects are addressed in millions of surgeries worldwide each year, in diverse fields such as orthopedic, neurocranial, plastic, and oral and dental surgery. Segmental bone defects can be the result of congenital abnormalities, or can arise secondarily from diverse causes such as trauma, malignancy, or infection. In adult patients, a critical defect of long bones is defined as a bone loss involving >50% of the circumference or >2 cm in length. 1 The available techniques to surgical manage these conditions are mainly based on bone grafting, distraction osteogenesis, and the induced membrane technique. 2 These approaches require long times of recovery and Stefano Negri and Yiyun Wang contributed equally to this work.

NGF-p75 signaling coordinates skeletal cell migration during bone repair

“…NMCCs or human calvarial osteoblasts were seeded in 24-well plates at a density of 1 × 10 5 cells/well. Osteogenic differentiation medium (ODM) consisted of α-MEM, 10% FBS, 1% penicillin/streptomycin with 100 nM dexamethasone, 50 μM ascorbic acid, and 10 mM βglycerophosphate (40)(41)(42). 24 h after cell seeding, growth medium was replaced with ODM, replenished every 3-4 d. For alizarin red (AR) staining, cells were fixed with 4% paraformaldehyde and stained with a 2% alizarin red solution at 14 d of differentiation.…”

Supercritical Carbon Dioxide Decellularized Bone Matrix Seeded with Adipose-Derived Mesenchymal Stem Cells Accelerated Bone Regeneration

“…In addition, ASC not only establishes outstanding cell expansion properties and osteogenic regeneration potential but also exhibits immunomodulatory properties. In addition, scaffolds are required for tissue-engineering applications to deliver cells and act as templates for tissue regeneration [ 25 ]. ASC-derived treatments have potential usage for cell-augmented bone repair approaches.…”

Wnt signaling activation: targets and therapeutic opportunities for stem cell therapy and regenerative medicine

“…Several studies have shown that DKK1 neutralizing monoclonal antibodies (anti-DKK1 mAbs) can accelerate bone formation and increase bone mineral density in various animal models. 54–58 BHQ880, 59 DKN-01, 60 and PF-04840082 61 are anti-DKK1 mAbs developed recently, and BHQ880 and DKN-01 are in clinical trials for patients with multiple myeloma and solid tumors, such as cholangiocarcinoma, esophageal cancer, and gastric cancer. 11 Anti-DKK1 mAbs may also be applicable for the treatment of immune evasion in cancer patients with DKK1 upregulation.…”