Current status of platelet-rich plasma therapy under the act on the safety of regenerative medicine in Japan

In Japan, a legal framework has been established for the safe and effective application of regenerative medicine. After eight years of the Act on the Safety of Regenerative Medicine (RM Act), discussions have been underway in the Ministry of Health, Labor and Welfare of Japan to revise the law owing to numerous novel technologies and inappropriate case reports not anticipated when the law was enacted. Therefore, in this review article, we have reviewed the regenerative medicine provision plans and the contribution of platelet-rich plasma (PRP) therapy, a regenerative medicine technique widely used in Japan post RM Act implementation, to these plans. As of January 2022, 97.2% of the regenerative medicine provided under the RM Act had been for private practice, and most of them were Class Ⅲ regenerative medicine. Notably, PRP was the most used processed cell under the RM Act. PRP therapy accounted for approximately 66% of the regenerative medicine provision plans in clinical research or private practice and was the most provided regenerative medicine technology in Japan. PRP therapy was primarily used in dentistry to regenerate periodontal tissue (approximately 50%), followed by orthopedics, where it is used to treat osteoarthritis. We suggest that further discussion is essential to determine the factors that should be addressed by the RM act to evaluate the efficacy and safety of PRP therapy.

Application to Butterbur Products of a Suggested Daily Intake-Based Safety Evaluation of Individual Herbal Supplements with Cytochrome P450 Expression as a Major Index

The present paper first proposes a method for ensuring the safety of commercial herbal supplements, termed the suggested daily intake-based safety evaluation (SDI-based safety evaluation). This new method was inspired as a backward analog of the acceptable daily intake (ADI) derivation from the no observed adverse effect level (NOAEL), the basis of food additive risk analysis; namely, rats are dosed with individual herbal supplement products at the SDI for human use multiplied by 100 (the usual uncertainty factor value) per body weight for 8 d. The primary endpoint is the sign of adverse effects on liver, especially gene expression of cytochrome P450 (CYP) isoforms. The proposed method was then applied to three butterbur (Petasites hybridus) products without pyrrolizidine alkaloids but lacking clear safety information. Results showed that two oily products markedly enhanced the mRNA expression of CYP2B (>10-fold) and moderately enhanced that of CYP3A1 (<4-fold) with liver enlargement. These products also caused the renal accumulation of alpha 2-microglobulin. One powdery product showed no significant effect on liver and kidney. The large difference in effects of products was due to the difference in chemical composition revealed by liquid chromatography-mass spectroscopy. The oily and the powdery products required attention in terms of safety and effectiveness, respectively. Finally, the results from the SDI-based safety evaluation of butterbur and other herbal supplement products were grouped into four categories and cautionary notes were discussed. The SDI-based safety evaluation of their products by herbal supplement operators would contribute to safe and secure use by consumers.

Internalization and Decrease of Duodenal DMT1 Involved in Transient Suppression of Iron Uptake in Short-Acting Mucosal Block

Mucosal block (MB) is induced by the oral administration of excess iron (10 mg) and suppresses intestinal iron absorption for 3-72 h. The inhibition of iron absorption is accompanied by the downregulation of molecules associated with intestinal iron absorption. Recently, we found that a smaller amount of iron (1 mg) also induced a transient suppression of iron uptake without affecting gene expression levels (short-acting mucosal block, SAMB), which is specific to iron-deficient rats. In this study, we investigated how the nonheme iron transporters divalent metal transporter 1 (DMT1) and ferroportin (FPN) are involved in the transient suppression of iron uptake in SAMB. To induce SAMB, a test solution containing 1 mg iron was infused into the duodenum loop in iron-sufficient and iron-deficient rats. Total duodenal DMT1 and DMT1-IRE expression were increased during iron deficiency. After 15 min of 1 mg iron loading, the fluorescence intensity of duodenal DMT1 in iron-deficient rats was decreased and was comparable to that in iron-sufficient rats. Internalized DMT1-IRE as puncta was observed at 15 and 60 min after 1 mg iron loading, and the number of punctas was significantly increased after 60 min compared with control. There was no effect of 1 mg iron loading on the intracellular distribution of duodenal FPN. Our results suggest that the decrease and internalization of DMT1-IRE protein may be related, at least in part, to iron uptake suppression in SAMB.

Marginally excessive iron loading transiently blocks mucosal iron uptake in iron-deficient rats

Regular "mucosal block" is characterized by decreased uptake of a normal iron load 3-72 h after the administration of excess iron (generally 10 mg) to iron-deficient animals. We found that short-acting mucosal block could be induced by much lower iron concentration and much shorter induction time than previously reported, without affecting levels of gene expression. A rapid endocytic mechanism was reported to decrease intestinal iron absorption after a high iron load, but the activating iron load and the time to decreased absorption were undetermined. We assessed the effects of 30-2,000 μg iron load on iron uptake in the duodenal loop of iron-deficient and iron-sufficient rats under anesthesia. One hour later, mucosal cellular iron uptake in iron-deficient rats administered 30 μg iron was 76.1%, decreasing 25% to 50.7% in rats administered 2,000 μg iron. In contrast, iron uptake by iron-sufficient rats was 63% (range 60.3-65.5%) regardless of iron load. Duodenal mucosal iron concentration was significantly lower in iron-deficient than in iron-sufficient rats. Iron levels in portal blood were consistently higher in iron-deficient rats regardless of iron load, in contrast to the decreased iron uptake on the luminal side. Iron loading blocked mucosal uptake of marginally excess iron (1,000 μg), with a greater effect at 15 min than at 30 min. The rapid induction of short-acting mucosal block only in iron-deficient rats suggests DMT1 internalization.

High dose of commercial products of kava (Piper methysticum) markedly enhanced hepatic cytochrome P450 1A1 mRNA expression with liver enlargement in rats

Commercial products containing the kava plant (Piper methysticum), known to have the anxiolytic activity, are banned in several European countries and Canada because of the suspicion of a potential liver toxicity. In some reports, kava and kavalactones (major constituents of kava) inhibited activities of cytochrome P450 (CYP) isoforms including CYP1A2. On the other hand, a few studies showed that administration of kava to rats moderately increased CYP1A2 proteins in the liver. CYP1A isoforms are likely responsible for the metabolic activation of potent carcinogenic environmental toxins such as aflatoxins, benzo[a]pyrene, and others. On these bases, we have investigated the effects of administration of commercial kava products on gene expression of hepatic CYP1A isoforms in rats. A high dose (equivalent to approximately 380mg kavalactones/kg/day; 100 times of the suggested dosage for human use) of two different types of kava products for 8 days significantly increased liver weights. CYP1A2 mRNA expression was moderately increased (2.8-7.3 fold). More importantly, the high dose of kava markedly enhanced CYP1A1 mRNA expression (75-220 fold) as well as ethoxyresorufin O-deethylase activities and CYP1A1 immunoreactivities. Thus, no observed adverse effect levels of kavalactones would be lower than 380mg/kg/day. When the safety factor of kavalactones is assumed to be 100, a value most often used upon the risk analysis of chemicals and designed to account for interspecies and intraspecies variations, a number of kava product users likely ingest more kavalactones than acceptable daily intakes. Based on overall evidence, we should pay considerable attention to the possibility that kava products induce hepatic CYP1A1 expression in human especially in sensitive individuals.

[Laminin-dependent growth arrest of human hepatic carcinoma cell line, HuH-7, in association with expression of p21/WAF-1 protein]

Laminin-overlay to the culture of a human hepatocellular carcinoma cell line, HuH-7, resulted in changes in the cell behavior; suppression of the cell growth, conversion of the cell morphology, and the elevated secretion of cellular AFP in the culture medium, implying that the cells had undergone apparent differentiation in vitro. Together with the behavioral changes, the cells showed positive immunohistochemical staining of the anti-p 21/WAF 1 antibody over the cell nucleus and the amount of p 21/WAF-1 proteins was increased in the cells. p53 protein was detected both in the control cells and the cells with the laminin overlay. These findings indicate that the laminin-dependent changes in the cell behavior are closely associated with the activation of the cyclin-dependent kinase inhibitor, p 21/WAF-1, and that? is uncoupled with the p 53 expression.

Adenomyoma of the common hepatic duct

A very rare case of adenomyoma of the common hepatic duct is described. A 54-year-old woman was admitted with impending obstructive jaundice secondary to adenomyoma of the common hepatic duct. Our impression, formulated from her clinical presentation, endoscopic investigations, and biochemical and radiological findings, was a cancer of the proximal common hepatic duct. The patient was treated successfully by combination surgical resection and hepaticojejunostomy. Despite our obtaining an intraoperative frozen section, final histological examination was required to confirm the diagnosis. The patient remains well 16 months postoperatively. A survey of the world literature revealed that this is the second report of adenomyoma occurring in the common hepatic duct.

Heterotopic gastric mucosa of the gallbladder

A case of heterotopic gastric mucosa in the fundus of the gallbladder is reported. A 23-year-old man, who had been healthy and asymptomatic, visited our hospital because of abnormal findings in a liver enzyme test given during a routine health screening. Ultrasonography demonstrated a highly echogenic polypoid mass in the fundus of the gallbladder. The gallbladder mass was confirmed by both computed tomography and intravenous cholangiogram. After a 10-month follow up, laparoscopic cholecystectomy was performed. Intraoperative touch smear cytology of this lesion revealed class II cells. The surgical specimen revealed a 15 x 10 x 5 mm polypoid lesion in the fundus, with no gallstones in the gallbladder. Histologically, the polypoid lesion consisted of both fundic type and pyloric type gastric glands located in the mucosa of the gallbladder. In the literature, 42 cases of heterotopic gastric mucosa of the gallbladder have been reported, only 3 of which, including this present case, were found incidentally, with no apparent symptoms.

[Acute respiratory failure based on liver dysfunction in canine liver ischemia model]

From the analysis of 182 consecutive surgical patients who underwent hepatectomy and/or were associated with liver cirrhosis during 1963-1982, acute respiratory failure was proved to be so much often in those patients. The case rate of this complication tends to increase according to resected size of liver tissue and severity of liver cirrhosis. Those cases showed clinical signs of pulmonary interstitial edema and were often associated with coagulopathy and endotoxemia. In order to clarify the pathophysiological mechanism of the acute respiratory failure based on liver dysfunction, a canine experimental model in which blood inflow into the liver was completely blocked was newly devised, and respiratory state in this model was analysed. The following results were obtained. The increase of EVLW (extravascular lung water) measured by modified double indicator dilution method was linear to the increase of PWP (pulmonary wedge pressure) in both liver failure group and control group. But the coefficient of the regression line was three times larger in the former group than in the latter. It suggests that permeability of pulmonary capillary was highly increased in liver failure group. All dogs with liver failure showed typical symptomes of lung edema at maximal PWP. Disseminated intravascular coagulation, consumption of neutrophils, decrease of CH50 and serum opsonin were thought to be mediators of the increase of lung vascular permeability. Steroid and PGI2 blocked the increase of the lung vascular permeability completely but not the increase of lung vascular resistance in this experimental model.

Hyperpolarizing responses in the soma of crayfish median giant fiber

Hyperpolarizing responses of the somata of median giant fibers of crayfish were investigated under current clamp and voltage clamp conditions in normal saline. The responses consisted of a peak [mean delta Vm (peak)=-217 mV] followed by a plateau (-107 mV), and could be classified into N-type and G-type. In the N-type cells, the current clamp I-V curve showed a transient phase to the peak. The phase corresponded to the negative slope region of the voltage clamp I-V curve. There was no negative slope region in the G-type cells. In the transient and the peak phases, the instantaneous I-V curves showed nonlinearity, and the shifts of the electromotive forces (delta EMF) from the resting level were slightly negative or zero. In the plateau phase, however, the instantaneous I-V curve was linear and delta EMF was large and positive (33.2 mV). The membrane resistance, which was larger (X2.3) at the peak than at the resting state, decreased (X0.23) gradually during the plateau phase. delta EMF during the hyperpolarizing response consisted of two components: a fast component (1.7 msec) and a slow one (113 msec). The amplitudes of delta EMF (27.4 mV) of these components in the depolarizing direction increased gradually, once the response had reached the peak. The fast and slow delta EMF's attained 17.0 and 10.4 mV respectively at the end of 100 msec current pulse. It is shown that constant charge triggers the plateau process and that this threshold voltage-current curve is hyperbolic. It is a possibility that the plateau is caused by membrane breakdown.

Impedance changes during the electrical and mechanical activities of a bullfrog heart

Electrical impedance of a bullfrog ventricle was recorded epicardially by the V-I method and the bridge method together with an electrocardiogram (ECG) and a contraction curve, in terms of shortening. Impedance change during one cardiac cycle of a contracting ventricle corresponded completely to the contraction curve in its time course: impedance decreased during systole and attained minimum at the peak of contraction, and the durations of both curves were almost identical. The ratio of impedance just before T-wave to that just after R-wave ([ZT]/[ZR]) of an in situ heart was increased when the ventricle contracted isovolumetrically by means of mineral oil: the ratio was far less than 1.0 in control ventricle, while it was more than 1.0 in oil-filled one (2/3 cases). Upon isometric condition or treatment of cadmium the motion restricted ventricle caused an increase in the impedance ratio ([ZT]/[ZR]) to higher than 1.0, as in the case of oil-filled ventricle. The epicardial recording of ventricular impedance seems to consist of two components: contraction(shortening-dependent impedance change, which reflects the membrane activity. Vigorous contraction will probably mask the latter and reveal only the former.

Effects of cadmium on the impedance locus of the abdominal skin of the bullfrog (Rana catesbeiana)

An impedance locus consisting of two superimposed semicircular arcs was revealed on the abdominal skin of the bullfrog. The decrease of skin resistance upon epidermal application of Cd (2 mM), which was related to Na active transport, proved to be due solely to the reduction in the size of the high frequency arc.

Cadmium-induced decrease in the outer facing skin resistance of a bullfrog (Rana catesbeiana)

Effects of cadmium on the electrical properties of frog skin were investigated by using the microelectrode technique. The epidermal application of 2 mM Cd for 5 min increased both the short circuit current and the skin potential, and decreased the skin resistance (RM). Cadmium also decreased intracellular potential with reference to the epidermal solution (PDi) and the electrical resistance between the epidermal solution and the tip of a microelectrode (RM1) located in the stratum germinativum. deltaRM that is RM,Cd-RM, control seemed to approximately coincide with deltaRM1 which is RM1,Cd-RM1,control. Comparing with our previous results, i.e., Cd decreased RNa (the resistance to the active Na current) and increased Rsigma (the resistance to the passive ions) but did not altered ENa (the electromotive force of active Na current) in the later stage (15 min or later). Cd seemed to decrease the RNa component at the epidermal side of the skin in the early stage (less than 5 min).

Effects of cadmium on the active transport of sodium by the abdominal skin of a bullfrog (Rana catesbeiana)

Effects of Cd on the active transport of Na in SO4-Ringer's solution on the abdominal skin of a bullfrog (Rana catesbeiana) were investigated. The short circuit current (SCC), potential difference (PD), and Na flux were determined. The skin resistance (Rm), the electromotive force of active Na transport (Ena), and the resistance to the active Na current (Rna) were calculated from the measured data. The application of Cd to the epidermal side at 2 mM was more effective in increasing SCC than that to the dermal side at the same concentration. The time course of changes in SCC induced by Cd were classified into three types: (I) a simple increase in SCC during Cd application, (II) an early decrease followed by an increase in SCC, and (III) a decrease in SCC except for a small increase in the initial short period. Type I response was observed in the majority of cases (about two-thirds). Types II and III were observed in 7 and 32 percent of 28 cases, respectively. The Cd-induced changes in SCC were analyzed on the basis of changes in ENa and RNa. In Type I, the increase in SCC was due to a remarkable decrease in RNa without an appreciable change in ENa (since SCC = ENa/RNa). In Types II and III, the changes in SCC in the early and the later stages could be explained by the differences in the extents to which ENa and RNa decreased. The experimental and calculated ratios of PDcd to PDcontrol in these stages were in good agreement with each other.