Hany E. Marei

Human microbiome and its association with health and diseases

Human microbiota are distinct communities of microorganisms that resides at different body niches. Exploration of the human microbiome has become a reality due to the availability of powerful metagenomics and metatranscriptomic analysis technologies. Recent advances in sequencing and bioinformatics over the past decade help provide a deep insight into the nature of the host‐microbial interactions and identification of potential deriver genes and pathways associated with human health, well‐being, and predisposition to different diseases. In the present review, we outline recent studies devoted to elucidate the possible link between the microbiota and various type of diseases. The present review also highlights the potential utilization of microbiota as a potential therapeutic option to treat a wide array of human diseases. J. Cell. Physiol. 231: 1688–1694, 2016.

Pseudomonas aeruginosa: arsenal of resistance mechanisms, decades of changing resistance profiles, and future antimicrobial therapies.

Antimicrobial resistance is one of the most serious public health issues facing humans since the discovery of antimicrobial agents. The frequent, prolonged, and uncontrolled use of antimicrobial agents are major factors in the emergence of antimicrobial-resistant bacterial strains, including multidrug-resistant variants. Pseudomonas aeruginosa is a leading cause of nosocomial infections. The abundant data on the increased resistance to antipseudomonal agents support the need for global action. There is a paucity of new classes of antibiotics active against P. aeruginosa. Here, we discuss recent antibacterial resistance profiles and mechanisms of resistance by P. aeruginosa. We also review future potential methods for controlling antibiotic-resistant bacteria, such as phage therapy, nanotechnology and antipseudomonal vaccines.

Mesenchymal Stem Cells in the Treatment of Traumatic Brain Injury

Traumatic brain injury (TBI) is characterized by a disruption in the normal function of the brain due to an injury following a trauma, which can potentially cause severe physical, cognitive, and emotional impairment. The primary insult to the brain initiates secondary injury cascades consisting of multiple complex biochemical responses of the brain that significantly influence the overall severity of the brain damage and clinical sequelae. The use of mesenchymal stem cells (MSCs) offers huge potential for application in the treatment of TBI. MSCs have immunosuppressive properties that reduce inflammation in injured tissue. As such, they could be used to modulate the secondary mechanisms of injury and halt the progression of the secondary insult in the brain after injury. Particularly, MSCs are capable of secreting growth factors that facilitate the regrowth of neurons in the brain. The relative abundance of harvest sources of MSCs also makes them particularly appealing. Recently, numerous studies have investigated the effects of infusion of MSCs into animal models of TBI. The results have shown significant improvement in the motor function of the damaged brain tissues. In this review, we summarize the recent advances in the application of MSCs in the treatment of TBI. The review starts with a brief introduction of the pathophysiology of TBI, followed by the biology of MSCs, and the application of MSCs in TBI treatment. The challenges associated with the application of MSCs in the treatment of TBI and strategies to address those challenges in the future have also been discussed.

Common and Rare Genetic Variants Associated With Alzheimer's Disease

Alzheimers disease (AD) is one of the most devastating disorders. Despite the continuing increase of its incidence among aging populations, no effective cure has been developed mainly due to difficulties in early diagnosis of the disease before damaging of the brain, and the failure to explore its complex underlying molecular mechanisms. Recent technological advances in genome‐wide association studies (GWAS) and high throughput next generation whole genome, and exome sequencing had deciphered many of AD‐related loci, and discovered single nucleotide polymorphisms (SNPs) that are associated with altered AD molecular pathways. Highlighting altered molecular pathways linked to AD pathogenesis is crucial to identify novel diagnostic and therapeutic AD targets. J. Cell. Physiol. 231: 1432–1437, 2016.

Common and Rare Variants Associated with Alzheimer's Disease

Alzheimers disease (AD) is one of the most devastating disorders. Despite the continuing increase of its incidence among aging populations, no effective cure has been developed mainly due to difficulties in early diagnosis of the disease before damaging of the brain, and the failure to explore its complex underlying molecular mechanisms. Recent technological advances in genome‐wide association studies (GWAS) and high throughput next generation whole genome, and exome sequencing had deciphered many of AD‐related loci, and discovered single nucleotide polymorphisms (SNPs) that are associated with altered AD molecular pathways. Highlighting altered molecular pathways linked to AD pathogenesis is crucial to identify novel diagnostic and therapeutic AD targets. J. Cell. Physiol. 231: 1432–1437, 2016.

Cholinergic and dopaminergic neuronal differentiation of human adipose tissue derived mesenchymal stem cells

Mesenchymal stem cells (MSCs) are multipotent cells that can differentiate into various cell types such as cartilage, bone, and fat cells. Recent studies have shown that induction of MSCs in vitro by growth factors including epidermal growth factor (EGF) and fibroblast growth factor (FGF2) causes them to differentiate into neural like cells. These cultures also express ChAT, a cholinergic marker; and TH, a dopaminergic marker for neural cells. To establish a protocol with maximum differentiation potential, we examined MSCs under three experimental culture conditions using neural induction media containing FGF2, EGF, BMP‐9, retinoic acid, and heparin. Adipose‐derived MSCs were extracted and expanded in vitro for 3 passages after reaching >80% confluency, for a total duration of 9 days. Cells were then characterized by flow cytometry for CD markers as CD44 positive and CD45 negative. MSCs were then treated with neural induction media and were characterized by morphological changes and Q‐PCR. Differentiated MSCs expressed markers for immature and mature neurons; β Tubulin III (TUBB3) and MAP2, respectively, showing the neural potential of these cells to differentiate into functional neurons. Improved protocols for MSCs induction will facilitate and ensure the reproducibility and standard production of MSCs for therapeutic applications in neurodegenerative diseases.

Potential of Stem Cell-Based Therapy for Ischemic Stroke

Ischemic stroke is one of the major health problems worldwide. The only FDA approved anti-thrombotic drug for acute ischemic stroke is the tissue plasminogen activator. Several studies have been devoted to assessing the therapeutic potential of different types of stem cells such as neural stem cells (NSCs), mesenchymal stem cells, embryonic stem cells, and human induced pluripotent stem cell-derived NSCs as treatments for ischemic stroke. The results of these studies are intriguing but many of them have presented conflicting results. Additionally, the mechanism(s) by which engrafted stem/progenitor cells exert their actions are to a large extent unknown. In this review, we will provide a synopsis of different preclinical and clinical studies related to the use of stem cell-based stroke therapy, and explore possible beneficial/detrimental outcomes associated with the use of different types of stem cells. Due to limited/short time window implemented in most of the recorded clinical trials about the use of stem cells as potential therapeutic intervention for stroke, further clinical trials evaluating the efficacy of the intervention in a longer time window after cellular engraftments are still needed.

Advances in osteobiologic materials for bone substitutes

A significant challenge in the current orthopedics is the development of suitable osteobiologic materials that can replace the conventional allografts, autografts, and xenografts and thereby serve as implant materials as bone substitutes for bone repair or remodelling. The complex biology behind the nanostructure and microstructure of bones and their repair mechanisms, which involve various types of chemical and biomechanical signalling amongst different cells, has set strong requirements for biomaterials to be used in bone tissue engineering. This review presents an overview of various types of osteobiologic materials to facilitate the formation of the functional bone tissue and healing of the bone, covering metallic, ceramic, polymeric, and cell‐based graft substitutes, as well as some biomolecular strategies including stem cells, extracellular matrices, growth factors, and gene therapies. Advantages and disadvantages of each type, particularly from the perspective of osteoinductive and osteoconductive capabilities, are discussed. Although the numerous challenges of bone regeneration in tissue engineering and regenerative medicine are yet to be entirely addressed, further advancements in osteobiologic materials will pave the way towards engineering fully functional bone replacement grafts.

Genetically unmatched human iPSC and ESC exhibit equivalent gene expression and neuronal differentiation potential.

The potential uniformity between differentiation and therapeutic potential of human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs) remains debatable. We studied the gene expression profiles, pathways analysis and the ability to differentiated into neural progenitor cells (NPCs) and motor neurons (MNs) of genetically unmatched integration-free hiPSC versus hESC to highlight possible differences/similarities between them at the molecular level. We also provided the functional information of the neurons derived from the different hESCs and hiPSCs lines using the Neural Muscular Junction (NMJ) Assay. The hiPSC line was generated by transfecting human epidermal fibroblasts (HEF) with episomal DNAs expressing Oct4, Sox2, Klf4, Nanog, L-Myc and shRNA against p53. For the hESCs line, we used the NIH-approved H9 cell line. Using unsupervised clustering both hESCs and hiPSCs were clustered together implying homogeneous genetic states. The genetic profiles of hiPSCs and hESCs were clearly similar but not identical. Collectively, our data indicate close molecular similarities between genetically unmatched hESCs and hiPS in term of gene expression, and signaling pathways. Moreover, both cell types exhibited similar cholinergic motor neurons differentiation potential with marked ability of the differentiated hESCs and hiPSCs-derived MNs to induce contraction of myotubes after 4 days of co-culture.

The effect of triiodothyronine on maturation and differentiation of oligodendrocyte progenitor cells during remyelination following induced demyelination in male albino rat

Demyelination was induced by two weeks cuprizone treatment. Rats of +ve control and triiodothyronine (T3) then received three subcutaneous injections of either saline or T3 day after day and sacrificed at the end of the third and fifth weeks. Animals in -ve control group received only standard rodent chow. After one week of cuprizone withdrawal the corpus callosum in +ve control and T3 treated rats was still demyelinated as revealed by MBP immunohistochemistry. The assay of PLP gene showed significant increase of T3 treated group compared to both the -ve control and +ve control groups. After three weeks, significant improvement in myelination was detected in T3-treated group compared to +ve control as detected by both MBP immunohistochemistry and electron microscopy. After one week of cuprizone withdrawal, PDGFRα positive cells and gene expression showed significant increase in +ve control and T3-treated groups as compared to -ve control with insignificant difference in between the former two groups. After three weeks of cuprizone withdrawal, PDGFRα positive cells in T3-treated and +ve control groups decreased to the control levels. These results suggest that T3 was effective in improving remyelination when administered during acute phase and might direct progenitor lineage toward oligodendrocytes.