The Dynamic Duo: Niche/Stem Cell Interdependency

Mesa, Kailin R.; Rompolas, Panteleimon; Greco, Valentina

doi:10.1016/j.stemcr.2015.05.001

Cited by 31 publications

(33 citation statements)

References 39 publications

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“…This extensive contact between the FP and SHG during telogen certainly has an adhesive role, keeping the FP in place under severe mechanical stress in the upper skin layers. This intimate association undoubtedly has a communicative significance as well . The basement membrane that separates the epithelial cells of the SHG and mesenchymal cells of the FP is relatively thick and multilayered (Figure E).…”

Section: The Secondary Hair Germ Is a Distinct Structure In The Mouse Hfmentioning

confidence: 95%

“…Furthermore, in some publications, these designations are used concurrently, thus producing a great deal of ambiguity. All in all, the currently prevailing view is that during telogen, the HF stem cell pool is composed of two compartments—the bulge and the SHG . Consequently, the SHG is simply considered as a “second stem cell population” [eg] or, more specifically, as a population of “primed stem cells” .…”

Section: Does the Shg Harbour A Stem Cell Population?mentioning

confidence: 99%

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Functional anatomy of the hair follicle: The Secondary Hair Germ

Panteleyev

2018

Experimental Dermatology

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The secondary hair germ (SHG)-a transitory structure in the lower portion of the mouse telogen hair follicle (HF)-is directly involved in anagen induction and eventual HF regrowth. Some crucial aspects of SHG functioning and ontogenetic relations with other HF parts, however, remain undefined. According to recent evidence (in contrast to previous bulge-centric views), the SHG is the primary target of anagen-inducing signalling and a source of both the outer root sheath (ORS) and ascending HF layers during the initial (morphogenetic) anagen subphase. The SHG is comprised of two functionally distinct cell populations. Its lower portion (originating from lower HF cells that survived catagen) forms all ascending HF layers, while the upper SHG (formed by bulge-derived cells) builds up the ORS. The predetermination of SHG cells to a specific morphogenetic fate contradicts their attribution to the "stem cell" category and supports SHG designation as a "germinative" or a "founder" cell population. The mechanisms of this predetermination driving transition of the SHG from "refractory" to the "competent" state during the telogen remain unknown. Functionally, the SHG serves as a barrier, protecting the quiescent bulge stem cell niche from the extensive follicular papilla/SHG signalling milieu. The formation of the SHG is a prerequisite for efficient "precommitment" of these cells and provides for easier sensing and a faster response to anagen-inducing signals. In general, the formation of the SHG is an evolutionary adaptation, which allowed the ancestors of modern Muridae to acquire a specific, highly synchronized pattern of hair cycling.

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Section: The Secondary Hair Germ Is a Distinct Structure In The Mouse Hfmentioning

confidence: 95%

Section: Does the Shg Harbour A Stem Cell Population?mentioning

confidence: 99%

Functional anatomy of the hair follicle: The Secondary Hair Germ

Panteleyev

2018

Experimental Dermatology

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“…It is today widely recognized the presence of stem cells in almost all adult tissues [11,12] and they exhibit superior powers such as the ability for self-renewal, growth, and differentiation into a variety of cell phenotypes [13–15]. The conventional in vitro cell expansion approach where cells are grown on smooth and stiff tissue culture plastic under media conditions and lacking necessary stimulatory cues is challenging [16], with cells undergoing phenotypic drift and senescence leading to poor clinical translation of promising therapies [17].…”

Section: Introductionmentioning

confidence: 99%

Engineered stem cell niche matrices for rotator cuff tendon regenerative engineering

et al. 2017

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Rotator cuff (RC) tears represent a large proportion of musculoskeletal injuries attended to at the clinic and thereby make RC repair surgeries one of the most widely performed musculoskeletal procedures. Despite the high incidence rate of RC tears, operative treatments have provided minimal functional gains and suffer from high re-tear rates. The hypocellular nature of tendon tissue poses a limited capacity for regeneration. In recent years, great strides have been made in the area of tendonogenesis and differentiation towards tendon cells due to a greater understanding of the tendon stem cell niche, development of advanced materials, improved scaffold fabrication techniques, and delineation of the phenotype development process. Though in vitro models for tendonogenesis have shown promising results, in vivo models have been less successful. The present work investigates structured matrices mimicking the tendon microenvironment as cell delivery vehicles in a rat RC tear model. RC injuries augmented with a matrix delivering rat mesenchymal stem cells (rMSCs) showed enhanced regeneration over suture repair alone or repair with augmentation, at 6 and 12-weeks post-surgery. The local delivery of rMSCs led to increased mechanical properties and improved tissue morphology. We hypothesize that the mesenchymal stem cells function to modulate the local immune and bioactivity environment through autocrine/paracrine and/or cell homing mechanisms. This study provides evidence for improved tendon healing with biomimetic matrices and delivered MSCs with the potential for translation to larger, clinical animal models. The enhanced regenerative healing response with stem cell delivering biomimetic matrices may represent a new treatment paradigm for massive RC tendon tears.

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“…Stem cells require a specialized microenvironment, or niche, comprised of support cells and signaling factors to coordinate stem cell maintenance with production of new cells for tissue renewal, organ regeneration, and tissue expansion (Mesa et al, 2015). Niche dysregulation is implicated in diseases, including leukemia (Wiseman, 2011; Zambetti et al, 2016), myelodysplastic syndrome (Hoggatt et al, 2016), Alzheimer’s disease (Hamilton et al, 2015), medulloblastoma (Bassett et al, 2016), and testicular germ cell tumors (Silván et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Identification of regulators of germ stem cell enwrapment by its niche in C. elegans

Linden

Gordon

Pani

et al. 2017

Developmental Biology

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Many stem cell niches contain support cells that increase contact with stem cells by enwrapping them in cellular processes. One example is the germ stem cell niche in C. elegans, which is composed of a single niche cell termed the distal tip cell (DTC) that extends cellular processes, constructing an elaborate plexus that enwraps germ stem cells. To identify genes required for plexus formation and to explore the function of this specialized enwrapping behavior, a series of targeted and tissue-specific RNAi screens were performed. Here we identify genes that promote stem cell enwrapment by the DTC plexus, including a set that specifically functions within the DTC, such as the chromatin modifier lin-40/MTA1, and others that act within the germline, such as the 14-3-3 signaling protein par-5. Analysis of genes that function within the germline to mediate plexus development reveal that they are required for expansion of the germ progenitor zone, supporting the emerging idea that germ stem cells signal to the niche to stimulate enwrapping behavior. Examination of wild-type animals with asymmetric plexus formation and animals with reduced DTC plexus elaboration via loss of two candidates including lin-40 indicate that cellular enwrapment promotes GLP-1/Notch signaling and germ stem cell fate. Together, our work identifies novel regulators of cellular enwrapment and suggests that reciprocal signaling between the DTC niche and the germ stem cells promotes enwrapment behavior and stem cell fate.

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The Dynamic Duo: Niche/Stem Cell Interdependency

Cited by 31 publications

References 39 publications

Functional anatomy of the hair follicle: The Secondary Hair Germ

Functional anatomy of the hair follicle: The Secondary Hair Germ

Engineered stem cell niche matrices for rotator cuff tendon regenerative engineering

Identification of regulators of germ stem cell enwrapment by its niche in C. elegans

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