Insight in Hypoxia-Mimetic Agents as Potential Tools for Mesenchymal Stem Cell Priming in Regenerative Medicine.

Hypoxia-mimetic agents are new potential tools in MSC priming instead of hypoxia incubators or chambers. Several pharmaceutical/chemical hypoxia-mimetic agents can be used to induce hypoxia in the tissues: deferoxamine (DFO), dimethyloxaloylglycine (DMOG), 2,4-dinitrophenol (DNP), cobalt chloride (CoCl2), and isoflurane (ISO). Hypoxia-mimetic agents can increase cell proliferation, preserve or enhance differentiation potential, increase migration potential, and induce neovascularization in a concentration- and stem cell source-dependent manner. Moreover, hypoxia-mimetic agents may increase HIF-1α, changing the metabolism and enhancing glycolysis like hypoxia. So, there is clear evidence that treatment with hypoxia-mimetic agents is beneficial in regenerative medicine, preserving stem cell capacities. These agents are not studied so wildly as hypoxia but, considering the low cost and ease of use, are believed to find application as pretreatment of many diseases such as ischemic heart disease and myocardial fibrosis and promote cardiac and cartilage regeneration. The knowledge of MSC priming is critical in evaluating safety procedures and use in clinics. In this review, similarities and differences between hypoxia and hypoxia-mimetic agents in terms of their therapeutic efficiency are considered in detail. The advantages, challenges, and future perspectives in MSC priming with hypoxia mimetic agents are also discussed.

Adhesion of Triple-Negative Breast Cancer Cells under Fluorescent and Soft X-ray Contact Microscopy.

Understanding cancer cell adhesion could help to diminish tumor progression and metastasis. Adhesion mechanisms are currently the main therapeutic target of TNBC-resistant cells. This work shows the distribution and size of adhesive complexes determined with a common fluorescence microscopy technique and soft X-ray contact microscopy (SXCM). The results presented here demonstrate the potential of applying SXCM for imaging cell protrusions with high resolution when the cells are still alive in a physiological buffer. The possibility to observe the internal components of cells at a pristine and hydrated state with nanometer resolution distinguishes SXCM from the other more commonly used techniques for cell imaging. Thus, SXCM can be a promising technique for investigating the adhesion and organization of the actin cytoskeleton in cancer cells.

[Photodynamic reaction and oxidative stress - influence of the photodynamic effect on the activity antioxidant enzymes]. / Reakcja fotodynamiczna a stres oksydacyjny - wplyw efektu fotodynamicznego na aktywnosc enzymów antyoksydacyjnych.

The interaction of light with a photosensitizer, accumulated in a tissue in the presence of oxygen, leads to formation of reactive oxygen species, mainly of singlet oxygen and free radicals. These factors react with biomolecules producing their oxidized states. Reactive oxygen species, such as singlet oxygen and free radicals are able to damage membranes, DNA, enzymes, structural peptides and other cellular structures leading to cell death. An antioxidant protection of cell is formed by enzymes belonging to the family of oxidoreductases: superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR). Photodynamic therapy leads to the increased production of oxidizing toxic forms. It is important to analyze impact of PDT on the activity of antioxidant enzymes, such as SOD, CAT, GPx. The activity of antioxidant enzymes during the photodynamic effect is influenced by both the light energy dose and the concentration of photosensitizer. The presence only of the photosensitizer or only the light energy may also result in changes in the activity of these enzymes. The differences in changes in the activity of these enzymes depend on the type of used photosensitizer. A phenomenon of selective accumulation of photosensitizer in tumor tissues is used in the photodynamic method of tumor diagnosis and treatment.

[The importance of stem cells in the initiation and development of cancer]. / Znaczenie komórek macierzystych w inicjacji i rozwoju nowotworów.

Initiation of cancer may be the result of mutations occurring in stem cells, which causes blocking the differentiation of these cells. Many common properties of the stem cells and some tumor cells suggests that cancer stem cells may be responsible for the initiation and progression of cancer. The special properties of CSC is the ability to self-renewal and cell proliferation, which are the major cause of cancer recurrence and metastasis. Signaling pathways (Wnt, Notch, Shh) and pluripotency- connected transcription factors (Oct-4, Nanog) are primarily responsible for cell proliferation. Understanding the causes of initiation and progression of cancer is crucial for improving treatment of these life-threatening diseases.

[Photodynamic method of cancer diagnosis and therapy--mechanisms and applications]. / Metoda fotodynamiczna diagnostyki i leczenia nowotworów--mechanizmy i zastosowania.

Cancers are diagnosed in over few millions patients annually. Due to inter alia weak antigenicity as well as drug-fastness of most cancers, PDT can become an effective alternative or complementary method to surgery. Photodynamic method requires tree elements: photosensitizer, light energy source and oxygen. Photodynamic therapy is successfully used method in many clinics all over the world, also in Poland. PDT is used in treatment of oncological (cancers of head, neck, lung, oesophagus, pancreas, urinary bladder and ginecological cancers) as non oncological diseases (lischen sclerosus, staphylococcus aureus, papillomatosis).

Cytotoxicity of PP(Arg)2- and PP(Ala)2(Arg)2-based photodynamic therapy and early stage of apoptosis induction in human breast cancers in vitro.

Mitochondria are cell energetic centers where ATP is produced. They also play a very important role in the PDT as intracellular sites of photosensitizer localization. Photosensitizers gathering in mitochondria (like porphyrin derivatives used in this work) are more effective in tumor cell destruction. Moreover, it was assumed that di-amino acid substituents attached to porphyrin ring will strengthen the effectivity of interaction with membrane receptors of examined cells. MTT assay was performed to investigate the influence of PP(Arg)(2) and PP(Ala)(2)(Arg)(2)-based PDT on breast cancer cell viability for 24 h, 48 h and 120 h after cell irradiation. Then the influence of PP(Ala)(2)(Arg)(2)- and PP(Arg)(2)-mediated PDT on early mitochondrial apoptosis induction via measurements of the transmembrane mitochondrial potential changes was examined. Results showed that lower energy doses and maximal nontoxic photosensitizer doses of PP(Ala)(2)(Arg)(2) and PP(Arg)(2) applied in PDT can imply apoptotic cell death. It was confirmed that modification of the protoporphyrin IX by attaching two alanine substituents raised the efficiency of photodynamic therapy.

Cytotoxicity of PP(Arg)(2)- and Hp(Arg)(2)-mediated photodynamic therapy and early stage of apoptosis induction in prostate carcinoma in vitro.

Porphyrin photosensitizers tend to localize in mitochondria. The depolarization of mitochondrial membrane is one of the early stages of apoptosis and Laser Scanning Fluorescence Microscopy allows to determine changes in transmembrane mitochondrial potential under influence of PDT depending on the kind of photosensitizer (PP(Arg)(2), Hp(Arg)(2)), the energy dose (5, 10, 30 and 50 J/cm(2)) and time periods (24 and 48 hours after irradiation) in the LNCaP (lymphonodal metastasis of prostate carcinoma, the androgen dependent cell line). Cyototoxicity induced by PP(Arg)(2)- and Hp(Arg)(2)-based PDT depending on energy dose and time after irradiation in prostate carcinoma is determined with MTT. Generally, it was shown that lower energy doses induce greater changes in transmembrane mitochondrial potential. Hp(Arg)(2)-based PDT was more effective causing greater mitochondrial membrane depolarization and cell viability decrease in comparison to PP(Arg)(2)-mediated PDT (in the case of maximal nontoxic photosensitizer doses used).

Inhibition of cell growth induced by photosensitizer PP(Arg)2-mediated photodynamic therapy in human breast and prostate cell lines. Part I.

Photodynamic therapy can become an effective alternative method to surgery. The experiments reveal that using low photosensitizer doses and relatively low energy doses allow us to obtain effective results after PDT (to limit formation of colonies by investigated cancer cells). The prostate and breast cancer cell lines were investigated: MCF-7, a human breast cancer responsive to androgen therapy; MDA-MB231, a more aggressive human breast cancer non-responsive to androgen therapy; LNCaP, a lymphonodal metastasis of prostate carcinoma responsive to androgen therapy; DU-145, a human prostate cancer non-responsive to androgen therapy. Clonogenic assay shows that certain PP(Arg)(2) and light energy low doses stimulate the researched colony-forming cancer cells growth. Some low energy doses used during PP(Arg)(2)-mediated PDT also cause the increase in the colony-forming tumor cells. Among investigated cancer lines, MCF-7 exhibited the biggest sensibility towards PP(Arg)(2) and LNCaP the smallest one. PP(Arg)(2) based PDT is an effective method in colony growth limitation of breast cancer cell lines: MCF-7, MDA-MB231 and prostate cancer cell lines: LNCaP, DU-145.