Clearance mechanism of protoporphyrin IX from mouse skin after application of 5-aminolevulinic acid

An innovative approach to detect circulating tumor cells

In cancer research, circulating tumor cells (CTCs) were identified as the main drivers of metastasis. They are vital for early detection and prevention of metastasis during cancer treatment. Even though continuous progress in research offers more and more tools to combat cancer, we still lack a proper arsenal of therapeutics. Especially in tumors with close to no targeting options, like triple-negative breast cancer, early detection is often the main difference between successful and failed therapy. When such tumors are detected too late, they may have already produced plenty of CTCs, likely causing metastasis, which is the primary reason for tumor-associated deaths. Detecting those CTCs early on could substantially impact therapy outcomes and the 5-year survival rate. In our study, we developed and evaluated a reliable and affordable CTC screening method based on flow cytometry and 5-aminolevulinic acid (5-ALA) staining. We successfully established a circulation model for 5-ALA and CTCs research and demonstrated that the method can detect an average of 11 ± 3.3 CTCs out of 10,000 peripheral blood mononuclear cells, representing as low as approximately 0.1 % with a reasonable number of false positive events. Additionally, we present initial results on a theranostic approach using 5-ALA converted to protoporphyrin IX. The outcomes of this study might contribute significantly to the further development of CTC detection and the overall detection and treatment of cancer.

Description of mitochondrial oxygen tension and its variability in healthy volunteers

OBJECTIVES

Describing mitochondrial oxygenation (mitoPO2) and its within- and between-subject variability over time after 5-aminolevulinic acid (ALA) plaster application in healthy volunteers.

DESIGN

Prospective cohort study.

SETTING

Measurements were performed in Leiden University Medical Center, the Netherlands.

PARTICIPANTS

Healthy volunteers enrolled from July to September 2020.

INTERVENTIONS

Two ALA plasters were placed parasternal left and right, with a 3-hour time interval, to examine the influence of the calendar time on the value of mitoPO2. We measured mitoPO2 at 4, 5, 7, 10, 28, and 31 hours after ALA plaster 1 application, and at 4, 5, 7, 25, and 28 hours after ALA plaster 2 application.

PRIMARY AND SECONDARY OUTCOME MEASURES

At each time point, five mitoPO2 measurements were performed. Within-subject variability was defined as the standard deviation (SD) of the mean of five measurements per timepoint of a study participant. The between-subject variability was the SD of the mean mitoPO2 value of the study population per timepoint.

RESULTS

In 16 completed inclusions, median mitoPO2 values and within-subject variability were relatively similar over time at all time points for both plasters. An increase in overall between-subject variability was seen after 25 hours ALA plaster time (19.6 mm Hg vs 23.9 mm Hg after respectively 10 and 25 hours ALA plaster time).

CONCLUSIONS

The mitoPO2 values and within-subject variability remained relatively stable over time in healthy volunteers. An increase in between-subject variability was seen after 25 hours ALA plaster time warranting replacement of the ALA plaster one day after its application.

TRIAL REGISTRATION

ClinicalTrials.gov with trial number NCT04626661.

Combination of 5-aminolevulinic acid and ferrous ion reduces plasma glucose and hemoglobin A1c levels in Zucker diabetic fatty rats

Mitochondrial dysfunction is associated with type 2 diabetes mellitus (T2DM). 5‐Aminolevulinic acid (ALA), a natural amino acid produced only in the mitochondria, is a precursor of heme. Cytochromes that contain heme play an important role in aerobic energy metabolism. Thus, ALA may help reduce T2DM‐associated hyperglycemia. In this study, we investigated the effect of ALA combined with sodium ferrous citrate (SFC) on hyperglycemia in Zucker diabetic fatty (ZDF) rats. We found that the gavage administration of ALA combined with SFC (ALA/SFC) for 6 weeks reduced plasma glucose and hemoglobin A1c (HbA1c) levels in rats without affecting plasma insulin levels. The glucose‐lowering effect depended on the amount of ALA/SFC administered per day. Furthermore, the glucose tolerance was also significantly improved by ALA/SFC administration. Although food intake was slightly reduced in the rats administered ALA/SFC, there was no effect on their body weight. Importantly, ALA/SFC administration induced heme oxygenase‐1 (HO‐1) expression in white adipose tissue and liver, and the induced expression levels of HO‐1 correlated with the glucose‐lowering effects of ALA/SFC. Taken together, these results suggest that ALA combined with ferrous ion is effective in reducing hyperglycemia of T2DM without affecting plasma insulin levels. HO‐1 induction may be involved in the mechanisms underlying the glucose‐lowering effect of ALA/SFC.

Protoporphyrin IX: the Good, the Bad, and the Ugly

Protoporphyrin IX (PPIX) is ubiquitously present in all living cells in small amounts as a precursor of heme. PPIX has some biologic functions of its own, and PPIX-based strategies have been used for cancer diagnosis and treatment (the good). PPIX serves as the substrate for ferrochelatase, the final enzyme in heme biosynthesis, and its homeostasis is tightly regulated during heme synthesis. Accumulation of PPIX in human porphyrias can cause skin photosensitivity, biliary stones, hepatobiliary damage, and even liver failure (the bad and the ugly). In this work, we review the mechanisms that are associated with the broad aspects of PPIX. Because PPIX is a hydrophobic molecule, its disposition is by hepatic rather than renal excretion. Large amounts of PPIX are toxic to the liver and can cause cholestatic liver injury. Application of PPIX in cancer diagnosis and treatment is based on its photodynamic effects.

Chitosan-based mucoadhesive films containing 5-aminolevulinic acid for buccal cancer's treatment

Photodynamic therapy (PDT) is a relatively new method to treat various kinds of tumors, including those of the oral cavity. The topical 5-ALA-PDT treatment for tumors of the oral mucosa is preferred, since when administered systemically, there is a general photosensitization drawback in the patient. However, 5-ALA is a hydrophilic molecule and its penetration and retention is limited by topical route, including oral mucosa. We propose a topical delivery system of chitosan-based mucoadhesive film, aiming to promote greater retention of 5-ALA in tissue. The chitosan (CHT) films (4% w/w) were prepared using the solvent evaporation/casting technique. They were tested without 5-ALA resulting in permeability to water vapor (W.V.P=2.15-8.54 g mm/(h cm(2)Pa) swelling ∼300.0% (±10.5) at 4 h or 24 h and in vitro residence time >24 h for all tests. CHT films containing 10.0% (w/w) 5-ALA have resulted in average weight of 0.22 g and thickness of 0.608 mm as suitable characteristics for oral application. In the presence of CHT films both in vitro permeation and retention of 5-ALA (1.0% or 10.0%) were increased. However, 10.0% 5-ALA presented highest values of permeation and retention (∼4 and 17 times respectively, compared to propylene glycol vehicle). On the other hand, in vitro mucoadhesion of CHT films was decreased (18.2-fold and 3.1-fold) by 5-ALA addition (1.0% or 10.0% respectively). However, CHT film containing 10.0% of 5-ALA can be a potential delivery system for topical use in the treatment of tumors of the oral cavity using PDT because it favored the retention of 5-ALA in this tissue and has shown convenient mucoadhesion.

Comparison of 5-aminolevulinic acid photodynamic therapy and red light for treatment of photoaging

OBJECTIVE

The aim of this pilot study was to compare the efficacy of ALA-PDT and red light alone in the treatment of photoaging.

METHODS

A total of 14 adults with photoaging skin were recruited. ALA-PDT or red light alone was applied to the forearm extensor. Before and after treatment, the treated sites were examined by dermoscopy, the changes in straum corneum (SC) hydration, transepidermal water loss (TEWL), and the L*a*b* values were measured, and microscopic examination of collagens and elastins was performed.

RESULTS

After ALA-PDT or red light illumination, the appearance of photoaging lesions improved, SC hydration increased and TEWL decreased. These changes in the ALA-PDT group were more obvious than those in the red light group. No significant change was noticed in the L*a*b* values in both groups. The signs of typical solar elastosis damage were improved in both groups.

CONCLUSIONS

ALA-PDT showed better skin rejuvenation effect than red light alone.