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Mesenchymal Stem Cells (MSCs), have been defined and characterized by: 1) their ability to adhere to plastic culture flasks; 2) the positive expression of CD105, CD73, CD90 membrane antigens, and the lack of expression of others (e.g CD45 and CD34) and 3) the ability of differentiation under adequate conditions along the osteogenic, chondrogenic and adipogenic lineages. In recent years, cells with these characteristics have been isolated from the Whartons jelly of the Umbilical Cord (UC). Similarly to bone marrow MSCs, they have shown multilineage differentiation potential and to be able to provide trophic support to neighboring cells. According to the literature, there are two main populations of cells with a mesenchymal character within the human UC: Whartons jelly Mesenchymal Stem Cells (WJ-MSCs) and Human Umbilical Cord Perivascular Cells (HUCPVCs). In the present work our aim is to make a comprehensive review on MSC populations of the UC and how these cell populations may be used for future applications in CNS regenerative medicine. Following a brief insight on the general characteristics of MSC like cells, we will discuss the possible sources of stem cells within the WJ and the cord itself (apart UC blood), as well as their phenotypic character. As it has already been shown that these cells hold a strong trophic support to neighbouring cell populations, we will then focus on their secretome, namely which molecules have already been identified within it and their role in phenomena such as immunomodulation. The possible applications of these cell populations to CNS regenerative medicine will be addressed by critically reviewing the work that has been performed so far in this field. Finally, a brief insight will be made on what in the authors opinion are the major challenges in the field for the future application of these cell populations in CNS regenerative medicine.

Stem cells have been long looked at as possible therapeutic vehicles for different health related problems. Among the different existing stem cell populations, Adipose derived Stem Cells (ASCs) have been gathering attention in the last 10 years. When compared to other stem cells populations and sources, ASCs can be easily isolated while providing higher yields upon the processing of adipose tissue. Similar to other stem cell populations, it was initially thought that the main potential of ASCs for regenerative medicine approaches was intimately related to their differentiation capability. Although this is true, there has been an increasing body of literature describing the trophic effects of ASCs on the protection, survival and differentiation of a variety of endogenous cells/tissues. Moreover, they have also shown to possess an immunomodulatory character. This effect is closely related to the ASCs secretome and the soluble factors found within it. Molecules such as hepatocyte growth factor (HGF), granulocyte and macrophage colony stimulating factors, interleukins (ILs) 6, 7, 8 and 11, tumor necrosis factor- (TNF-), vascular endothelial growth factor (VEGF), brain derived neurotrophic factor (BDNF), nerve growth factor (NGF), adipokines and others have been identified within the ASCs secretome. Due to its importance regarding future applications for the field of regenerative medicine, we aim, in the present review, to make a comprehensive analysis of the literature relating to the ASCs secretome and its relevance to the immune and central nervous system, vascularization and cardiac regeneration. The concluding section will highlight some of the major challenges that remain before ASCs can be used for future clinical applications.

Gender affirmation surgeries in male-to-female patient transitioning include breast augmentation, genital construction, and facial feminization surgery (FFS). FFS improves mental health and quality of life in transgender patients. The nose and forehead are critical in facial attractiveness and gender identity; thus, frontal brow reduction and rhinoplasty are a mainstay of FFS. The open approach to reduction of the frontal brow is very successful in the feminization of the face; however, risks include alopecia and scarring. Endoscopic brow reduction, in properly selected patients, is minimally invasive with excellent outcomes avoiding these risks. Since both reduction rhinoplasty and frontal brow reduction are routinely performed in FFS, a combined approach provides superior control over the nasal radix and profile when performing surgery on the frontal bone region first followed by nose reduction. We present a case series of four transwomen undergoing frontal bone reduction in combination with a reduction rhinoplasty. All had excellent results with one DVT that resolved with treatment. Transgender patients frequently require multiple operations during their transition increasing their hospital stay and costs. This combined approach offers superior control over the nasofrontal angle and is not only safe but reduces hospitalizations and costs and is a novel indication to reduce gender dysphoria.

Radial forearm free flap phalloplasty is the most commonly performed flap for neophallus construction in the female-to-male (FtM) transgender patient. Urological complications, however, can arise quite frequently and can prevent the patient from urinating in the standing position, an important postsurgical goal for many. Using mucosa to construct the fixed urethra and to prelaminate the penile urethra has been successful in reducing urologic complications, particularly strictures and fistulas. Until now, only buccal, vaginal, colonic, and bladder sites have been described as sources for these mucosal grafts. We present the successful use of uterine mucosa for prelamination of the neourethra in an FtM patient who underwent hysterectomy and vaginectomy at the prelamination stage of a radial forearm phalloplasty. Three months postoperatively, the patient was able to void while standing and showed no evidence of stricture or fistula on retrograde cystogram. These results suggest that uterine mucosa may be used for prelamination of the penile neourethra in patients undergoing phalloplasty.

Neurological disorders and injuries are typically chronic and debilitating diseases that frequently lead to the premature death of afflicted individuals, thereby imposing a harsh emotional burden on their family members. These disorders/injuries, which include neurodegenerative diseases (Parkinson and Huntington disease), epilepsy, neuromuscular disorders, spinal cord injury and stroke often pose unique challenges for treatment. Current therapies for CNS related disorders are based on the use of pharmacological agents, which often lead to serious side effects. Therefore there is a great interest in the possibility of repairing the nervous system by transplanting cells that can replace the lost cell populations or, in alternative, induce local neuronal proliferation, differentiation and consequent tissue regeneration. In the last years stem cells, and within them adult stem cells from different sources, have been in the forefront of a new wave of possible therapeutic strategies. In fact different routes have been followed so far. Some strategies are solely based on the transplantation and differentiation potential of different populations of stem cells, others rely on their trophic capability while some recent strategies are purely based on the sole administration of the secretome of stem cells. Other routes have also involved bioengineering approaches, where stem cells are combined with biomaterials, scaffolds and nanotechnology concepts, in order to develop therapies that target the above referred problems. This is in fact an exciting cutting edge field of science, where basic stem cells biology meets state of the art materials science with the common goal of improving the quality of life of afflicted patients. Therefore, I am glad and thankful that a panel of renowned scientists has joined this special issue on “Adult Stem Cells and Tissue Engineering in Central Nervous Regenerative Medicine” and reviewed the most recent data on different topics that may have a strong impact on the future of Central Nervous System Regeneration. I sincerely hope that this special issue contributes to future and important developments within this field. Finally, I would like to thank the editorial staff of Current Stem Cell Research & Therapy at Bentham Science Publishers for their help with the preparation of this special issue.