Feasibility of photodynamic therapy for secondary hyperparathyroidism in chronic renal failure rats
Feasibility of photodynamic therapy (PDT) for secondary hyperparathyroidism (SHPT) was examined in a rat model of SHPT.
A photosensitizer, 5-aminolevulinic acid (5-ALA), was injected intraperitoneally, and the parathyroid glands were irradiated either after surgical exposure with 385-nm light or transdermally with 630-nm light from a light-emitting diode (LED) lamp.
PDT with high 5-ALA and irradiation doses caused severe hypoparathyroidism in SHPT rats within two days. Low-dose invasive PDT reduced intact parathyroid hormone (iPTH) levels in all rats from 748.9 ± 462.6 pg/mL at baseline to 138.7 ± 117.5 pg/mL at week 6, followed by a further decrease to 80.5 ± 54.0 pg/mL at week 9 in 60 % of rats or an increase to 970.0 ± 215.6 pg/mL at week 9 in 40 % of rats. Low-dose noninvasive PDT reduced iPTH levels from 1612.5 ± 607.8 pg/mL at baseline to 591.9 ± 480.1 pg/mL at week 4 in all rats. Thereafter, iPTH levels remained low in 43 % of rats and were 233.7 ± 51.6 pg/mL at week 9, whereas 57 % showed an increase, reaching 3305.9 ± 107.3 pg/mL at week 9. Control SHPT rats had iPTH levels of 2487.8 ± 350.9 and 2974.6 ± 372.1 pg/mL at week 4 and 9, respectively. The parathyroid glands of the rats with low iPTH levels were atrophied and had few parathyroid cells surrounded by fibrotic materials and no recognizable blood vessels. Those of the rats with high iPTH levels showed well-preserved gland structure, clusters of parathyroid cells, and blood vessels.
These results demonstrate that 5-ALA-mediated PDT for SHPT is feasible.
Keywords5-Aminolevulinic acid Hyperparathyroidism Parathyroid gland Parathyroid hormone Photodynamic therapy
This study was supported by grants from Torii Pharmaceutical Co., Ltd., Kyowa Hakko Kirin Co., Ltd and Kidney Foundation Japan (grant No. 15J013). We thank Yukiko Seki, Hitomi Moriya and the Support Center for Medical Research and Education, Tokai University School of Medicine for their valuable technical assistance.
Compliance with ethical standards
Disclosure of potential conflict of interest
Kyowa Hakko Kirin Co. Ltd. Consultancy: Masafumi Fukagawa, Honoraria: Takatoshi Kakuta, Masafumi Fukagawa, Grants: Takatoshi Kakuta, Masafumi Fukagawa; Torii Pharmaceutical Co., Ltd. Grants: Takatoshi Kakuta; Kidney Foundation Japan. Grants: Takayo Miyakogawa. The other authors declare that they have no Conflict of interests. The funding organizations, Torii Pharmaceutical Co., Ltd., Kyowa Hakko Kirin Co., Ltd. and Kidney Foundation Japan played no roles in data collection and analysis or decision to publish.
All procedures performed in studies involving animal were in accordance with the ethical standards of the institution or practice at which the studies were conducted (IRB approval number 161016).
Research involving human participants and animals
This article does not contain any studies with human participants performed by any of the authors.
For this type of article, informed consent is not required.
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