Department of Pathology, University of Western Ontario, London, Canada.
Xenotransplantation. 2009 Nov-Dec;16(6):502-10. doi: 10.1111/j.1399-3089.2009.00548.x.
Islet transplantation is potentially a promising therapy for the restoration of carbohydrate control to diabetic patients. However, the global application of islet transplantation requires a ubiquitous source of beta cells. The xenotransplantation of porcine islets would provide such a source. Success in porcine islet xenografting has been achieved in diabetic primates. However, there are few reports of reversal of diabetes with porcine islet xenografts in rodent models of diabetes, relative to the number of successful rodent experiments performed as allografts. Here we report for the first time the inability of porcine (and human) insulin to control blood glucose levels in diabetic rodents determined by a series of dose escalating studies.
Insulin was administered intravenously to streptozotocin induced diabetic Lewis rats, Balb/c and athymic Balb/c mice (n = 5 per group) at the following doses: Group I "physiological dose" (pd) of 0.16 U/kg for a total dose of 40 mU to a 250 g rat. Group II received 0.64 U/kg (4xpd), group III 1.6 U/kg (10xpd) and group IV 6.4 U/kg (40xpd). Blood glucose levels were monitored in each animal at seven time points: 0 (pre-injection), 10 min, 20 min, 30 min, 45 min, 1 h, 1.5 h, 2 h and 3 h post-injection. Serum insulin levels were also determined.
Diabetic Lewis rats achieved a maximum reduction in blood glucose from 22.1 +/- 1.8mmol/l to 8.0 +/- 3.1 mmol/l (a 63.7% reduction), 90 minutes post-injection of 6.4 U/kg dose of porcine insulin (40xpd). Human insulin was less effective at reducing blood glucose levels in rats than porcine insulin (P < 0.001). Porcine insulin reduced blood glucose levels in Balb/c mice from a mean of 18.2 +/- 2.1 mmol/l to a hypoglycemic minimum of 1.26 +/- 0.18 mmol/l a reduction of 93.0%, 60 min post-injection of the maximum dose of 6.4 U/kg. Balb/c mice were significantly more responsive to porcine insulin than Lewis rats at doses of 0.64 U/kg (P < 0.001), 1.6 U/kg (P < 0.05) and 6.4 U/kg (P < 0.001). Athymic Balb/c nude mice reached a maximum reduction in blood glucose from 21.6 +/- 1.8 mmol/l to 3.6 +/- 0.9 mmol/l (a 83.4% reduction) 120 min post-injection at a dose of 6.4 U/kg. Overall, athymic Balb/c nude mice were more resistant to porcine insulin than immunocompetent Balb/c mice at doses of 0.64 U/kg (P < 0.001), 1.6 U/kg (P < 0.001) and 6.4 U/kg (P < 0.05). Insulin diluent alone marginally increased blood glucose levels in all animals tested.
Our results suggest that restoration of normoglycemia in diabetic rodents is not ideal for testing porcine islets xenografts since the reversals of diabetes in these species requires 20 to 40 times the dose of porcine insulin used in humans.
胰岛移植是一种有前途的治疗糖尿病患者碳水化合物控制的方法。然而，胰岛移植的全球应用需要无处不在的β细胞来源。猪胰岛的异种移植将提供这样的来源。在糖尿病灵长类动物中，猪胰岛异种移植已取得成功。然而，与作为同种异体移植进行的成功的啮齿动物实验数量相比，在糖尿病啮齿动物模型中，用猪胰岛异种移植物逆转糖尿病的报道很少。在这里，我们首次报告了猪（和人）胰岛素在一系列剂量递增研究中不能控制糖尿病啮齿动物的血糖水平。
用链脲佐菌素诱导的Lewis 大鼠、Balb/c 和无胸腺 Balb/c 小鼠（每组 5 只）静脉注射胰岛素，剂量如下：I 组“生理剂量”（pd），即 250 g 大鼠 40 mU 的 0.16 U/kg，总剂量为 40 mU。II 组接受 0.64 U/kg（4xpd），III 组接受 1.6 U/kg（10xpd），IV 组接受 6.4 U/kg（40xpd）。在 7 个时间点监测每组动物的血糖水平：0（注射前）、10 分钟、20 分钟、30 分钟、45 分钟、1 小时、1.5 小时、2 小时和 3 小时。还测定了血清胰岛素水平。
6.4 U/kg 剂量的猪胰岛素（40xpd）注射后 90 分钟，糖尿病 Lewis 大鼠的血糖从 22.1 ± 1.8mmol/l 最大降低至 8.0 ± 3.1 mmol/l（降低 63.7%）。猪胰岛素比人胰岛素更能有效降低大鼠的血糖水平（P < 0.001）。与 Lewis 大鼠相比，猪胰岛素在 Balb/c 小鼠中从平均 18.2 ± 2.1 mmol/l 降低至 1.26 ± 0.18 mmol/l 的低血糖最低值（降低 93.0%），60 分钟注射最大剂量 6.4 U/kg。与 0.64 U/kg（P < 0.001）、1.6 U/kg（P < 0.05）和 6.4 U/kg（P < 0.001）相比，Balb/c 小鼠对猪胰岛素的反应明显更为敏感。无胸腺 Balb/c 裸鼠在 6.4 U/kg 剂量下血糖最大降低，从 21.6 ± 1.8 mmol/l 降低至 3.6 ± 0.9 mmol/l（降低 83.4%），注射后 120 分钟。总的来说，与免疫功能正常的 Balb/c 小鼠相比，无胸腺 Balb/c 裸鼠对猪胰岛素的耐药性更强，在 0.64 U/kg（P < 0.001）、1.6 U/kg（P < 0.001）和 6.4 U/kg（P < 0.05）剂量下。胰岛素稀释剂本身仅使所有测试动物的血糖水平略有升高。
我们的结果表明，在糖尿病啮齿动物中恢复正常血糖水平并不理想，因为在这些物种中，糖尿病的逆转需要 20 到 40 倍于人类使用的猪胰岛素剂量。
