Physiologic homeostasis after pig-to-human kidney xenotransplantation

Demand for kidney grafts outpaces supply, limiting kidney transplantation as a treatment for kidney failure. Xenotransplantation has the potential to make kidney transplantation available to many more patients with kidney failure, but the ability of xenografts to support human physiologic homeostasis has not been established. A brain-dead adult decedent underwent bilateral native nephrectomies followed by 10 gene-edited (four gene knockouts, six human transgenes) pig-to-human xenotransplantation. Physiologic parameters and laboratory values were measured for seven days in a critical care setting. Data collection aimed to assess homeostasis by measuring components of the renin-angiotensin-aldosterone system, parathyroid hormone signaling, glomerular filtration rate, and markers of salt and water balance. Mean arterial blood pressure was maintained above 60 mmHg throughout. Pig kidneys secreted renin (post-operative day three to seven mean and standard deviation: 47.3 ± 9 pg/mL). Aldosterone and angiotensin II levels were present (post-operative day three to seven, 57.0 ± 8 pg/mL and 5.4 ± 4.3 pg/mL, respectively) despite plasma renin activity under 0.6 ng/mL/hr. Parathyroid hormone levels followed ionized calcium. Urine output down trended from 37 L to 6 L per day with 4.5 L of electrolyte free water loss on post-operative day six. Aquaporin 2 channels were detected in the apical surface of principal cells, supporting pig kidney response to human vasopressin. Serum creatinine down trended to 0.9 mg/dL by day seven. Glomerular filtration rate ranged 90-240 mL/min by creatinine clearance and single-dose inulin clearance. Thus, in a human decedent model, xenotransplantation of 10 gene-edited pig kidneys provided physiologic balance for seven days. Hence, our in-human study paves the way for future clinical study of pig-to-human kidney xenotransplantation in living persons.

0695 Sleepwell24, A Smartphone Application To Promote PAP Therapy Adherence: Feasibility And Acceptability

Introduction

We aimed to test the feasibility and acceptability of SleepWell24, a multicomponent, smartphone-delivered intervention to increase positive airway pressure (PAP) adherence among newly diagnosed OSA patients.

Methods

SleepWell24 targets PAP adherence along with other health behaviors through education, trouble-shooting, goal-setting, and near real-time biofeedback of PAP machine use, and sleep and physical activity levels (via Fitbit integration), and other chronic disease self-management components. Patients with a first-time diagnosis of OSA (AHI≥5) and prescribed PAP therapy were enrolled from the Centers for Sleep Medicine at Mayo Clinic in Rochester, MN and Phoenix, AZ. Patients were randomized to SleepWell24 or usual care (UC) and assessed for PAP use over 60 consecutive nights. UC patients received a Fitbit monitor to control for non-specific intervention effects related to the introduction of a new personal technology. Feasibility was assessed with recruitment and retention rates and acceptability was assessed post-intervention with the validated, 8-item Treatment Evaluation Questionnaire (TEQ; range:0-4). ANCOVA models, adjusting for age, sex, and AHI severity, compared intervention arms on acceptability ratings.

Results

OSA patients were consented and randomized (N=111). Before the intervention began 4 participants withdrew, 12 were lost to follow-up, and 5 could not start the trial due to durable medical equipment (DME) vendor barriers. Ninety OSA patients (n=41 SleepWell24, n=49 UC; age M±SD=57.2±12.2; 44.4% female, 61.1% AHI≥15) started the intervention, with 2 participants withdrawing, 1 becoming deceased (unrelated to treatment) and 7 with missing PAP data due to DME vendor barriers. There was no significant between-groups differences on post-treatment acceptability (SleepWell24 M±SD=2.7±1.1 vs. UC M±SD=3.1±0.9, F[1,73]=2.3, p=0.11), and 77% of SleepWell24 participants found the app to be moderately to totally acceptable.

Conclusion

Overall, SleepWell24 was found to be feasible for delivery in two large clinical sleep medicine centers, and patients found the app to be acceptable. A number of challenges in trial delivery were encountered that have implications for scaled-up efficacy testing: (a) partnerships with DME vendors for near real-time PAP data integration; (b) alignment with clinical practice (i.e., referral, medical record integration); and (c) patient engagement.

Support

National Institute of Nursing Research / National Institutes of Health: R21NR016046

Coordination of cecal motility during cecal evacuation

Turkeys were surgically prepared with two strain gauge transducers on each cecum to detect both major and minor contractions at each implant site and to allow appraisal of coordination of contractions within and between ceca at the time of cecal evacuation and at dawn. There were significantly more of both types of contractions and significantly more major than minor contractions immediately before than after evacuation. At dawn the frequency of minor contractions was significantly greater than that of major contractions and there were significantly more contractions immediately after dawn than before dawn. Contractile activity was more often not coordinated than coordinated at anytime both within and between the ceca. When there was coordination within each cecum before evacuation, it was more frequently orad oriented than aborad. Near dawn the occurrence of coordinated contractions within each cecum was not significantly different from the occurrence of no coordination and the latter occurred significantly more frequently than did coordination between the two ceca.