CD34 is a target for covalent EGFR inhibitors to eliminate stem/progenitor cells in acute and chronic myeloid leukemia

The effect of epidermal growth factor receptor (EGFR) inhibitors on acute myeloid leukemia (AML) was discovered over one decade ago. However, clinical trials of EGFR inhibitors in AML have yielded controversial outcomes. Leukemia cells lack EGFR expression, and the mechanism by which EGFR inhibitors affect leukemia cell growth is unknown, obscuring the precise subset of AML patients that might be targeted by these compounds. Since myeloid leukemia arises from malignant stem/progenitors, here we evaluated the effect of EGFR inhibitors on primary leukemia stem/progenitors that expressed the stem cell marker CD34 which were sorted from leukemia patients. EGFR inhibitors induced significant apoptosis of primary CD34+ but not CD34− cells derived from AML and chronic myeloid leukemia (CML) patients both in vitro and in patient-derived xenotransplantation model. Using two EGFR inhibitors osimertinib and afatinib, we demonstrated binding and covalent adducts of the inhibitors with the cysteine(C) 199 residue of the CD34 protein, which downregulated phosphorylation of tyrosine 329(Y329) of CD34, leading to the dissociation of CD34 from tyrosine kinase Src and thereafter the inhibition of STAT3 phosphorylation. Most importantly, administration of osimertinib yielded clinical responses in two CD34-high AML patients identified by quantitative proteomics with reduced levels of Y329 phosphorylation of CD34 after treatment. Collectively, these findings delineate a novel molecular pathway whereby EGFR inhibitors kill leukemia and reveal that the CD34 antigen is a targetable signaling molecule that mediates cell survival signals via connecting to Src-STAT3 pathway.

New lymphatic cell formation is associated with damaged brain tissue clearance after penetrating traumatic brain injury

We characterized the tissue repair response after penetrating traumatic brain injury (pTBI) in this study. Seventy specific pathogen-free Kunming mice were randomly divided into the following groups: normal control, 1, 3, 7, 15, 21, and 30 days after pTBI. Hematoxylin and eosin (H&E) staining, immunohistochemistry, and immunofluorescence were performed to examine and monitor brain tissue morphology, and the distribution and expression of lymphatic-specific markers lymphatic vessel endothelial receptor-1 (LYVE-1), hematopoietic precursor cluster of differentiation 34 (CD34) antigen, and Prospero-related homeobox-1 (PROX1) protein. H&E staining revealed that damaged and necrotic tissues observed on day 1 at and around the injury site disappeared on day 7, and there was gradual shrinkage and disappearance of the lesion on day 30, suggesting a clearance mechanism. We explored the possibility of lymphangiogenesis causing this clearance as part of the post-injury response. Notably, expression of lymphangiogenesis markers LYVE-1, CD34, and PROX1 was detected in damaged mouse brain tissue but not in normal tissue. Moreover, new lymphatic cells and colocalization of LYVE-1/CD34 and LYVE-1/PROX1 were also observed. Our findings of the formation of new lymphatic cells following pTBI provide preliminary insights into a post-injury clearance mechanism in the brain. Although we showed that lymphatic cells are implicated in brain tissue repair, further research is required to clarify the origin of these cells.

Analysis of the facial skin condition of a mature person before and after CGF Harmony

Facial skin aging has been in the sphere of human interest since the earliest times, but relatively recently, along with the new branch of medicine — aesthetics there have appeared opportunities both for its slowing down and the instrumental study of the process. Recently, the emphasis is on the use of autologous preparations, especially on the basis of the own blood, among which the promising procedure seems to be CGF Harmony (stem cells labeled with CD34+ antigen and concentrated growth factors). The aim of this paper was to assess both subjective and objectified matured facial skin before and after CGF Harmony administrations, based on medical photographic documentation (the Fotomedicus system) and instrumental examination of skin parameters (Cutometer Dual MPA 580). The presented results show high variability and dynamics of obtained values. At the same time, they suggest a sustained improvement in the visual correction of the face oval and flattening of wrinkles, perceived positively by both the patient and her surroundings, and amelioration visible in photographic and instrumental studies in terms of skin elasticity (parameters R2 and R7). From the research and the manufacturer's proposal, it appears that one should suggest treatments in a semi‑annual cycle preceded by facial skin examinations.

Different MACS sorting strategies for the enrichment of Lin– (CD34+ CD45–) hematopoietic progenitor cells: preliminary study

Magnetic-activated cell sorting (MACS) has become a standard method for the isolation of hematopoietic stem/progenitor cells (HSC/HPC) in human or mouse model using CD34 antibodies. However, at the present there is no useable CD34 antibody that could be successfully used for the selection of rabbit HSC/HPC. Therefore, the aim of this preliminary study was to remove all mature cells (CD45+) from the heterogeneous mixture of rabbit peripheral blood and bone marrow mononuclear cells (PBMCs and BMMCs) in order to enrich these cell populations for the CD34+ cells. Briefly, cells were incubated with a CD45 antibody and proper magnetic microbeads. Three different MACS sorting strategies were used in the experiment that differed mainly in the sample loading rate and the number of used magnetic columns. Control (unsorted) and sorted cells were assessed for the sorting efficiency (% of double positive cells for CD45 and Labelling Check Reagent – LCR) by flow cytometry and for the relative expression of CD34 antigen by qPCR. According to flow cytometry, Depl025 mode showed the best sorting efficiency in terms of the lowest percentages of CD45+LCR+ cells for rabbit PBMCs as well as BMMCs. qPCR analysis confirmed this mode as the best in terms of the relative CD34 expression for rabbit PBMCs. However, higher relative expression of CD34 in BMMCs was obtained by other mode – Posselds. In conclusion, this study demonstrates a possible enrichment of rabbit (CD34+) HSC/HPC by the magnetic depletion of mature hematopoietic (CD45+) cells.

Distribution of telocytes in the corpus and cervix of human uterus: an immunohistochemical study

Over the last few years, researchers have been studying telocytes, recently described interstitial cells, voraciously. This morphological study focused on the immunohistochemical identification of telocytes and the study of their topographical relations in the wall of the human uterine body and cervix. This study attempted to find the most specific and therefore, the most suitable monoclonal antibody for the study of telocytes via the immunohistochemical methods. Tissue specimens from human uteruses were stained with eight different primary antibodies, to detect the expression of c-kit (CD117), CD34 antigen, vimentin,

Peripheral blood stem cells: mobilization strategies and potential therapeutic applications

Peripheral blood stem cell (PBSC) transplantation is now a day’s preferred transplantation source of stem cells as treatment modality for various hematologic malignancies. Progenitor hematopoietic stem cells express CD34 antigen, through which PBSCs are selected and collected. Peripheral blood stem cells provide a rapid and effective hematopoietic recovery after administration in patients having hematological ailments, with the advantages of a shorter engraftment time and the lack of a need for surgical procedure necessary for bone marrow harvesting. PBSCs are routinely present in blood circulation; though number too low to be used for transplantation. PBSCs can be mobilized by the administration of G-CSF or GM-CSF alone or preceded by chemotherapy. The yield of stem cells after mobilization differ enormously with disease condition, age etc. and several studies have been performed with different mobilizing regimen and factors affecting yield of progenitor cells. Mobilized peripheral blood stem cells have been increasingly used clinically for many diseases including myeloma, leukemia, lymphoma etc. In the current review, we give brief introduction about peripheral blood stem cells, its advantages over bone marrow and emphasize on different mobilizing strategy used for mobilizing PBSCs and expansion of these PBSCs under in vitro environment. The potential clinical application of PBSCs in treating different diseases has also been reviewed here in detail.