Extended Data Fig. 9: Additional xenograft physiology data and ELISA testing of EPO and renin.

(A) Serum electrolyte levels for sodium, potassium, and magnesium, and repletion timings and doses for potassium and magnesium are shown. Serum electrolytes remained generally stable, with occasional repletion needed for potassium and magnesium. The median serum sodium was 141 mmol/L (IQR 137–142 mmol/L), the median serum potassium was 4.0 mmol/L (IQR 3.7–4.4 mmol/L), and the median serum magnesium was 1.9 mg/dL (IQR 1.7–2.1 mg/dL). (B) Hourly urine output (UOP), plasma arginine vasopressin (AVP) levels, serum sodium, and urine osmolality (Usom) were routinely monitored to evaluate xenograft water handling, alongside the corresponding vasopressin infusion rate outlined below. After an initial period of polyuria, UOP normalized within the first three days with urine concentration >600 mOsm/kg displayed within the first week post-transplant in the setting of ongoing exogenous vasopressin infusion. (C) Median plasma renin activity (PRA) and serum aldosterone levels remained low following bilateral nephrectomy and xenograft reperfusion, measuring on average 0.1 ng/mL/hr and <3.0 ng/dL, respectively. (D) Adrenocorticotrophic hormone stimulation test using cosyntropin IV 0.25 mg was performed. Plasma cortisol levels were measured at baseline, 30 min post injection, and 60 min post injection. Rise in cortisol after adrenal stimulation by cosyntropin demonstrated intact adrenal function in the decedent. (E) Results of the porcine EPO ELISA assay, with a lower limit of quantification (LLOQ) of 1 mIU/mL. Decedent serum samples tested for porcine EPO on POD 4 and POD 11 were undetectable. (F) Results of the porcine renin ELISA assay, with a LLOQ of 62.5 pg/mL. Decedent serum samples tested for porcine renin on POD 10 and 21 were below the LLOQ at 3.3 pg/mL and 0.7 pg/mL, respectively, so results should be considered below the reliable detection threshold. Porcine serum sample tested for porcine renin as a control was 207.8 pg/mL.