BPC 157 and fistulas closing. External (A–D) and internal (E, F) fistulas. External fistulas. (A) Persistent esophagocutaneous fistula and BPC 157 therapy effect. BPC 157 was given per-orally, in drinking water (10 μg/kg, 10 ng/kg, i.e., 0.16 μg/ml, 0.16 ng/ml, 12 ml/rat/day) until sacrifice, or intraperitoneally (10 μg/kg, 10 ng/kg) with first application at 30 min after surgery, last at 24 h before sacrifice. To establish NO-system involvement, L
-NAME (5 mg/kg i.p.) (worsening) and/or L
-arginine (100 mg/kg i.p.) (beneficial effect) were given alone or together; first application at 30 min after surgery, last at 24 h before sacrifice. BPC 157 (10 μg/kg, i.p. or p.o.) given with L
-NAME (5 mg/kg i.p.) and/or L
-arginine (100 mg/kg i.p.) and it maintained its original beneficial effect. A closely interrelated process of unhealed skin, esophageal defects, unhealed fistulas (upregulated eNOS, iNOS, and COX2 mRNA levels), usually lethal, particularly NO-system–related and therapy dependent, illustrate a largely open skin defect in controls at day 3 (c) and a closed skin defect in BPC 157 rats (b) (Ceserec et al., 2013). (B) Initial presentation of the persistent gastrocutaneous fistula and BPC 157 therapy effect. Huge gastrocutaneous fistula leaking at 1st postoperative day in control rats (c) and dried fistula without any leakage in BPC 157 rats (b (Skorjanec et al., 2009). The rats received pentadecapeptide BPC 157 (0.16 μg/ml) in drinking water (12 ml/rat) until sacrifice or drinking water only. A comparative study of the BPC 157 beneficial effect was done with intraperitoneal application, once daily, intraperitoneally (per kg body weight) 10 μg, 10 ng, or 10 pg BPC 157, while standard agents 10 mg atropine, 50 mg ranitidine, and 50 mg omeprazole provide only a weak effect. 6-alpha-methylprednisolone (1 mg/kg intraperitoneally, once daily) was given alone which produced a considerable worsening and was completely eliminated with coadministration of BPC 157 10 μg/kg intraperitoneally. (C) Persistent duodenocutaneous fistula and BPC 157 therapy effect. BPC 157 was given per-orally, in drinking water (10 μg/kg, 10 ng/kg, i.e., 0.16 μg/ml, 0.16 ng/ml, and 12 ml/rat/day) till sacrifice, or alternatively, 10 μg/kg and 10 ng/kg intraperitoneally; first application at 30 min after surgery, last at 24 h before sacrifice. To establish a connection with the NO-system, l
-NAME (5 mg/kg intraperitoneally) (worsening) and/or L
-arginine (100 mg/kg intraperitoneally) (beneficial effect) were given alone or together; first application at 30 min after surgery, last at 24 h before sacrifice. BPC 157 10 μg/kg, intraperitoneally or per-orally, was given with l
-NAME (5 mg/kg intraperitoneally) and/or L
-arginine (100 mg/kg intraperitoneally) and it maintained its original beneficial effect. Controls simultaneously received an equivolume of saline (5.0 ml/kg intraperitoneally) or water only. Duodenal fistula leaking through skin defect and still open duodenal defect at 2 weeks following fistula creation by anastomosis between the skin and duodenum defect (c). Closed both skin and duodenal defect in BPC 157 rats (fistula closed, b) (Skorjanec et al., 2015). (D) Persistent colocutaneous fistula and BPC 157 therapy effect. BPC 157 accelerated parenterally or per-orally the healing of colonic and skin defect, leading to the suitable closure of the fistula, macro/microscopically, biomechanically, and functionally (larger water volume sustained without fistula leaking) (Klicek et al., 2013). In anesthetized rats, we created the colocutaneous fistula at 5 cm from the anus, colon defect of 5 mm, and skin defect of 5 mm. The rats received pentadecapeptide BPC 157 (0.16 μg/ml) or nothing in the drinking water (12.0 ml/rat) until the sacrifice or once daily, intraperitoneally BPC 157 10.0 μg/kg, 10.0 ng/kg, or saline (5.0 ml/kg b.w.); first application at 30 min after surgery, final 24 h before sacrifice. For comparison, sulfasalazine (50 mg/kg intraperitoneally, once daily) (moderately effective) or 6-α-methylprednisolone (1.0 mg/kg intraperitoneally, once daily) (aggravation) was given. To establish connection with the NO-system, L
-NAME (5.0 mg/kg) (worsening) and L
-arginine (200.0 mg/kg) (effective only with blunted NO-synthesis, but not alone) were given intraperitoneally alone or in combination (d
-arginine 200.0 mg/kg was not effective, data not shown). BPC 157 given with NO-agents, which maintained its original effect. Initial colon defect presentation at 4 weeks following fistula creation by anastomosis between the skin and colon defect (c, middle). Presentation after next 2 weeks (c, b): in control rats, drinking water was continuously given (12 ml/day/rat) (defecation through fistula, c) and in BPC 157 rats, BPC 157 (10 μg/kg/day) was given in drinking water (0.16 μg/ml/day/rat) (fistula closed, b). Internal fistulas. (E) Persistent colovesical fistula and BPC 157 therapy effect. With internal fistulas in the colon and the bladder, with BPC 157 therapy, the colon and bladder defects showed simultaneous healing effects, including closing of the colovesical fistula in a matching healing process (Grgic et al., 2016). BPC 157 was given per-orally in drinking water (10 μg/kg, 12 ml/rat/day) until sacrifice, or 10 μg/kg or 10 ng/kg was given intraperitoneally once daily, with the first application at 30 min after surgery and the last application at 24 h before sacrifice. The controls simultaneously received an equivolume of saline (5.0 ml/kg ip) or water only (12 ml/rat/day). At postoperative day 28, voiding through fistula in controls (fecaluria) (c) and a normal voiding in BPC 157-rats (b). (F) Persistent rectovaginal fistula and BPC 157 therapy effect. We suggest BPC 157 healing of the rats’ rectovaginal fistulas (since spontaneous only poor healing as those in humans) as a realization of the internal fistula-healing concept, an efficient “wound-healing capability” as the therapy of the complicated internal fistula healing. BPC 157 was given per-orally, in drinking water (10 μg/kg or 10 ng/kg, 0.16 μg/ml, or 0.16 ng/ml 12 ml/rat/day) till sacrifice, or alternatively, 10 μg/kg and 10 ng/kg intraperitoneally once daily; first application at 30 min after surgery, last at 24 h before sacrifice. Controls simultaneously received an equivolume of saline (5.0 ml/kg ip) or water only (12 ml/rat/day). At postoperative day 21, defecation through vagina in controls (c) and a normal defecation in BPC 157 rats (b) (Baric et al., 2016).