Xenotransplantation of Microencapsulated Parathyroid Cells as a Potential Treatment for Autoimmune-Related Hypoparathyroidism

OBJECTIVES

Hypoparathyroidism occurs as a part of a complex autoimmune syndrome or iatrogenically after neck surgery. The disease presents many challenges, such as hypocalcemia, hyperphosphatemia, and low/undetectable parathormone levels. Allotransplantation of parathyroid tissue or cells has been reported as a promising option to overcome these effects. Transplantation of microencapsulated parathyroid tissue or cells offers an immune escape, which particularly restores the parathyroid function for autoimmune-related hypoparathyroidism. So far, clinical and in vivo studies have demonstrated limited graft survival and instability for the available biocompatible materials. In addition, the transplant site, proper local isolation, and biocompatibility of materials are directly related to survival rate.

MATERIALS AND METHODS

A microencapsulated parathyroid xenotransplant model by using high guluronic acid-containing ultrapure alginate transplanted into rat omentum was tested in vivo for 1 year.

RESULTS

After stability of empty microcapsules was ensured, parathyroid cells were microencapsulated and transplanted in rats, with results compared versus rats with naked (nonencapsulated) parathyroid cells (both groups followed for 64 weeks). Rats remained normocalcemic, and preinflammatory cytokine levels showed dramatic changes. Despite a delay posttransplant, parathormone levels increased significantly. All retrieved microencapsules elicited pericapsular fibrotic overgrowth; however, the fibrosis area was shown to be well tolerated.

CONCLUSIONS

The possible role of accumulation/cell infiltration of immune response remains to be elucidated. In conjunction with this, the use of nonencapsulated parathyroid cells was also positively correlated with survival rates. A similar evaluation using ultrapure alginate materials and omental transplantation may enable the future determination for the long-term effects of correction of parathormone insufficiency in patients with severe hypocalcemic responses and other endocrine diseases.

Fisetin decreases the duration of ictal-like discharges in mouse hippocampal slices

There is an increasing interest in the biological and therapeutic effects of fisetin, a natural phenolic compound. Fisetin has affinity on some neuronal targets and may have the potential to modulate neuronal activity. In this study the effects of acute application of fisetin on synchronized events were evaluated electro-physiologically. Besides, interaction of fisetin with closely related channels were investigated in silico. Acute horizontal hippocampal slices were obtained from 32- to 36-day-old C57BL/6 mice. Extracellular field potentials were recorded from CA3 region of the hippocampus. Bath application of 4 aminopyridine (4AP, 100 µM) initiated ictal- and interictal-like synchronized epileptiform discharges in the brain slices. Fifty micromolar fisetin was applied to the recording chamber during the epileptiform activity. The duration and frequencies of both ictal-like and interictal-like activities were calculated from the electrophysiological records. Molecular docking was performed to reveal interaction of fisetin on GABA-A, NMDA, AMPA receptors, and HCN2 channel, which are neuronal structures directly involved in recorded activity. Although fisetin does not affect basal neuronal activity in brain slice, it reduced the duration of ictal-like discharges significantly. Molecular docking results indicated that fisetin has no effect on GABA-A, NMDA, and AMPA receptors. However, fisetin binds to the (5JON) HCN2 channel strongly with the binding energy of -7.66 kcal/mol. Reduction on the duration of 4AP-induced ictal-like discharges can be explained as HCN channels can cause an inhibitory effect via enhancing M-type K + channels which increase K outward currents.

In silicoinvestigation of Alliin as potential activator for AMPA receptor

Natural products from plants, such as flavonoids, arouse immense interest in medicine because of the therapeutic and many other bioactive properties. The molecular docking is a very useful method to screen the molecules based on their free binding energies and give important structural suggestions about how molecules might activate or inhibit the target receptor by comparing reference molecules. Alliin and Allicin differ from many other flavonoids because of containing no benzene rings and having nitrogen and sulfur atoms in their structure. In this study Alliin and Allicin affinity on AMPA, NMDA and GABA-A receptors were evaluated in the central nervous system by using the molecular docking method. Both Alliin and Allicin indicated no inhibitory effects. However Alliin showed significant selectivity to human AMPA receptor (3RN8) as an excitatory. The binding energy of glutamate to 3RN8 was -6.61 kcal mol^-1, while the binding energy of Allin was -8.08 kcal mol^-1. Furthermore Alliin's affinity to the other AMPA and NMDA receptors is quite satisfactory compared to the reference molecule glutamate. In conclusion based on the molecular docking study, Alliin can be useful for synaptic plasticity studies whereas might be enhance seizure activity because of the increased permeability to cations. It also can be beneficial to improve learning and memory and can be used as a supportive product to the hypofunction of NMDA associated problems.

Synthesis and photodynamic efficacy of water-soluble protoporphyrin IX homologue with mPEG550

Protoporphyrin IX (PpIX), which is an efficient photosensitive agent, cannot be used directly in photodynamic therapy due to its aggregation in physiological environment. If PpIX is made water-soluble without losing its photosensitive properties, it can be used in many medical fields, including cancer treatment. Here we report synthesis of PpIX homologue with mPEG550 (Porfipeg) and its photodynamic effects on both in-vitro and in-vivo environment. Porfipeg is synthesized to give PpIX the ability to dissolve in water. Spectrometric (FT-IR, NMR, MS, UV-vis and Fluorescence) measurements were performed. Porfipeg can penetrate into the cells and indicates no cytotoxicity in the dark whereas cell viability significantly reduced with light irradiation. The cells can be visualized by fluorescence microscope. In-vivo experiment revealed that intravenous injection of Porfipeg is more efficient than intraperitoneal injection for the acute photodynamic effects within 30 min. Moreover it is excreted by the kidneys. In conclusion, Porfipeg has remarkable potentials to be used in both fluorescence guidance in surgeries and photodynamic therapy for cancer treatment.

A New Transport Solution for Parathyroid Allotransplantation: Effects on Cell Viability and Calcium-Sensing Receptors

BACKGROUND

Cold ischemia protects organs and tissues by slowing their metabolism, but it also causes ischemic injury. Minimizing cold ischemia has been an important goal in parathyroid auto- and allotransplantation, as well as the transplantation of other major organs. Parathyroid glands are responsible for calcium homeostasis by releasing parathormone (PTH) into the blood circulation. Functionality of a new parathyroid transport solution (NPTS) and effects on cell viability, PTH secretion, and calcium-sensing receptor (CaSR) levels during cold ischemia were evaluated.

MATERIALS AND METHODS

A NPTS was prepared, and the pH was adjusted to a range of 7.2-7.4 and kept at +4°C until use. Seven patients with parathyroid hyperplasia secondary to chronic renal failure who were scheduled to undergo subtotal parathyroidectomy were enrolled in the study. Glands were cold-preserved in NPTS with different time intervals (0, 6, 12, 18, and 24 hours), and then parathyroid cell viability before and after cryopreservation, PTH secretion, and CaSR levels were determined.

RESULTS

The mean cell viability before cryopreservation was 92.7% (range 89.2%-97.2%). There were no significant differences in cell viability rates before and after cryopreservation (p = 0.1168 and p = 0.4085, respectively), and CaSR levels (p = 0.5446) were not significant.

CONCLUSIONS

NPTS is a solution designed specifically for parathyroid tissue transplantation. This patent pending product can support cellular viability and PTH release, as well as protect CaSR functionality for up to 24 hours of cold ischemia.

Fresh tissue parathyroid allotransplantation with short-term immunosuppression: 1-year follow-up

BACKGROUND

Permanent hypoparathyroidism is a serious problem and requires medications indefinitely. Parathyroid allotransplantation (PA) with short-term immunosuppression is definitive choice but long-term results are not clear.

METHOD

We performed PA from two donors to two recipients. Both recipients were 39-year-old females. Donors were a 32-year-old female and a 36-year-old male, who both have chronic kidney disease. Routine tests, viral markers, and cross-matches were analyzed individually. The parathyroid glands were resected from the living donors, fragmented quickly in the operation room and injected into the left deltoid muscles of the two recipients.

RESULTS

Methylprednisolone was administered on post-PA day one and two. Recipients were discharged from the hospital without complications. Calcium and PTH levels were observed throughout 1 year. We did not observe any complications during the follow-up period. Medications ceased in post-transplantation week 1 for Case 1 and after 1 month for Case 2.

CONCLUSION

Fresh tissue PA with short-term immunosuppression appears to be a promising technique that is easy to perform, is cost-effective, has low risk of side effects and minimal complications with compatibility for HLA conditions. A longer follow-up period and more case studies are needed to determine the risks and benefits of this procedure for future cases.

Protoporphyrin IX-loaded magnetoliposomes as a potential drug delivery system for photodynamic therapy: Fabrication, characterization and in vitro study

BACKGROUND

Protoporphyrin IX (PpIX) is a well-known photosensitizer that has great potential for use in photodynamic therapy (PDT). However, aggregation behavior of PpIX in neutral water makes it inappropriate for physiological studies. PpIX-loaded magnetoliposomes (MLs) were fabricated to increase PpIX biocompatibility. PpIX-loaded ML physical properties were characterized, and PpIX-loaded ML drug release behavior was investigated under the influence of an external magnetic field and heat. Toxicity and photodynamic effects of the complex were also examined using in vitro experiments with MCF-7 human breast cancer cells.

METHODS

The magnetoliposomes were prepared with DPPC, DSPE-PEG2000 lipids and Fe3O4 nanoparticles. The toxicity and in vitro photodynamic effects of the PpIX-loaded MLs at various concentrations were studied using the MCF-7 cell line.

RESULTS

The produced PpIX-loaded MLs exhibited an average hydrodynamic diameter of 221nm; however, TEM measurements indicated that the diameter of the PpIX-loaded MLs varied between 166 and 720nm. The iron content of the MLs affected cell viability less than the content of the iron free liposomes. Cell viability was reduced to 66% when the concentration of the PpIX-loaded MLs was 350nM, but when white light was applied for 5min, all of the cells that were exposed to concentrations of 250nM and higher PpIX died within 24h.

CONCLUSION

The results of this study demonstrated the effective application of PpIX-loaded MLs for in vitro photodynamic therapy at nanomolar concentrations. The results also indicated that an LED light source provided sufficient energy to stimulate the PpIX molecules.

Cuprizone-induced demyelination in Wistar rats; electrophysiological and histological assessment

OBJECTIVES

Multiple Sclerosis (MS) is a disease that affects the Central Nervous System by destructing myelin shield and also can affects the peripheral nervous system. Demyelination is acquired characteristics disease and appears with the degeneration of myelin which protects the axons. Cuprizone (CPZ) model is a toxic demyelination model. The purpose of this study was to develop an MS model by cuprizone exposure to Wistar rats.

MATERIALS AND METHODS

Rats were separated into control and experimental groups and daily cuprizone was administered to experimental groups for 4, 5, 6 and 7 weeks. At the end of the experiments, spinal nerve conduction velocity was measured by EMG detected from the gastrocnemius muscle. After scarification, cerebrum and cerebellum of the animals were taken for histopathological investigation.

RESULTS

Spinal cord nerve conduction velocity (SNCV) of control animals was 76.54 m/s. Whereas SNCV of the rats that were feed with CPZ for 6 weeks was significantly reduced to 46.35 m/s in comparison with the control group. Demyelinated areas and vacuolization were seen on the brain sections of CPZ exposed rats.

CONCLUSIONS

SNCV of the rats were feed with cuprizone began tendency of decrease after 4th weeks. These reductions were observed as maximum at 6th weeks. At 7th week increments were observed at SNCV. These results indicated that 6 weeks of cuprizone feedings could be suitable to bring into existence of MS model in Wistar rats.