Angiogenic Therapy: Novel Approaches to Enhance Bone Regeneration in Aging - AD/ADRD

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SUMMARY Alzheimer’s Disease (AD) is the most common form of dementia in the elderly. Several studies have shown increased risk of fracture with dementia owing in part to increases in falls. On the flip side, several clinical studies have also demonstrated that a fracture history can increase the risk for dementia. The latter findings are associations. To further understand the link between fracture and AD, in this Supplement we will extend our current fracture healing studies as follows. We will complete surgically induced femoral fractures in the 5xFAD mouse model of AD mouse model AD and related dementias (AD/ADRD), where we will examine the progression/severity of AD/ADRD over 12 weeks post-surgery. Because poor angiogenesis is associated with AD/ADRD, we will also determine whether novel fracture healing agents known to improve angiogenesis and fracture healing (thrombopoietic agents or TMPs and sirtuin 1 activator or SRT1720) decrease AD/ADRD progression/severity. Based on these combined ideas, we hypothesize that fracture increases neurodegeneration, neuroinflammation, and the progression/severity of AD/ADRD in the 5xFAD mouse model. We further hypothesize that treatment of fractured mice with SRT1720 or TMP will improve angiogenesis, decrease neurodegeneration, decrease neuroinflammation, and slow/reduce the progression/severity of AD/ADRD. One Aim is proposed in this Supplement. Aim 1. Determine the effects of a femoral fracture and treatment of femoral fractures with SRT1720 or TMP on the progression/severity of AD/ADRD. To accomplish this 5xFAD mice will undergo baseline cognitive testing. Half of the mice will serve as uninjured controls and half of the mice will undergo a surgically induced femoral fracture. Mice will be treated with SRT1720, TMP, or vehicle control beginning at the time of surgery until mice are euthanized 12 weeks post-surgery. Fracture healing, cognitive decline, neurodegeneration, neuroinflammation, vascular biology, and the integrity of the blood brain barrier (BBB) will be assessed. Finally, we will collect brains and serum from mice from the Parent R01 (young [3-4 mo] and old [22-24 mo] mice on a C57BL/6 background without genetic alterations known to impact AD) to assess changes, as detailed above, based on fracture, treatment, and age. Successful completion of this aim will demonstrate whether progression/severity of AD/ADRD is worse following femur fracture. Importantly these studies may demonstrate that treatment of fractures with novel bone healing therapies SRT1720 and/or TMP, which are known to improve angiogenesis and fracture healing, may have the added benefit of attenuating the progression/severity of AD/ADRD.