Overweight females are prone to obesity-associated stress urinary incontinence (OA-SUI), but because the mechanisms underlying its pathology have not been well elucidated, no specific therapies for the condition have been developed. It is possible that dysfunction of urethral striated muscle contributes to OA-SUI, as atrophy of skeletal muscle often occurs in obese people. Activating endogenous stem/progenitor cells to regenerate damaged muscle could comprise a useful therapeutic approach. However, systemic administration of stem cells or their activators can cause dangerous side effects in off-target organs or tissues. Localized administration of curatives does not resolve this problem, because injected stem or progenitor cells often migrate outside the target area. Our laboratory, which has focused on the biology of endogenous stem/progenitor cells for the past 12 years, is developing a non-invasive method that can recruit and retain these cells at selected sites, or activate them in situ. Our pilot experiments demonstrate that low-energy shock waves (LESW) activates urethral muscle progenitor cells; they also down-regulate the muscle growth inhibitor myostatin. We hypothesize that by activating resident stem cells to grow new myofibers, LESW can reverse OA-SUI. To clarify mechanisms and identify potential clinical approaches, we are also investigating myostatin inhibition via a novel DNA-inhibiting method called clustered regularly interspaced short palindromic repeats interference (CRISPRi). We will use a rodent OA-SUI model to assess structural and functional outcomes of treatment with CRISPRi, LESW, or both, and compare the results with the effects of weight-loss (the usual treatment taken in the clinic). To elucidate how obesity affects the structure and function of the female urethral sphincter, the molecular mechanisms involved in activating its resident stem cells, and the impacts LESW has on their activation. We will also establish the feasibility of inducing regeneration of this muscle by inhibiting myostatin signaling. These objectives lead us to propose the following Specific Aims: 1. To validate an animal model useful for the study of obesity-induced alterations of urethral striated muscle. 2. To measure the structural and functional improvements in OA-SUI sphincter dysfunctions afforded by LESW compared with weight loss. 3. To increase sphincter recovery by myostatin inhibition in rats with OA-SUI. 4. To identify the effects of dyslipidemia and hyperglycemia on the survival, differentiation, and transcriptional signatures of stem cells through the modulation of myostatin signaling, and its counteraction by LESW.
The ability to activate and differentiate endogenous stem cells would be a powerful curative approach for many human diseases, and this ability is the basis of the technological innovations we are developing for locally enhancing muscle regeneration to treat obesity associated stress urinary incontinence (OA-SUI). A novel mechanobiological intervention we are developing will modulate these cells and evoke muscle regeneration in a non-invasive manner, without disturbing neighboring tissues or causing off-target effects. The project will also establish the feasibility of inducing regeneration of this muscle by inhibiting myostatin signaling with a new and more effective DNA-inhibiting method, the 'clustered regularly interspaced short palindromic repeats interference' (CRISPRi).
