scholarly journals Potential Effects of Corneal Cross-Linking upon the Limbus

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Johnny E. Moore ◽  
Davide Schiroli ◽  
C. B. Tara Moore
Keyword(s):  
Stem Cells ◽  
Potential Risk ◽  
Ocular Surface ◽  
Ex Vivo ◽  
Uv Exposure ◽  
Cross Linking ◽  
Clinical Complications ◽  
Cellular Dna ◽  
Pathological Consequence

Corneal cross-linking is nowadays the most used strategy for the treatment of keratoconus and recently it has been exploited for an increasing number of different corneal pathologies, from other ectatic disorders to keratitis. The safety of this technique has been widely assessed, but clinical complications still occur. The potential effects of cross-linking treatment upon the limbus are incompletely understood; it is important therefore to investigate the effect of UV exposure upon the limbal niche, particularly as UV is known to be mutagenic to cellular DNA and the limbus is where ocular surface tumors can develop. The risk of early induction of ocular surface cancer is undoubtedly rare and has to date not been published other than in one case after cross-linking. Nevertheless it is important to further assess, understand, and reduce where possible any potential risk. The aim of this review is to summarize all the reported cases of a pathological consequence for the limbal cells, possibly induced by cross-linking UV exposure, the studies donein vitroorex vivo, the theoretical bases for the risks due to UV exposure, and which aspects of the clinical treatment may produce higher risk, along with what possible mechanisms could be utilized to protect the limbus and the delicate stem cells present within it.

Strategies to Protect Hematopoietic Stem Cells from Culture-Induced Stress Conditions

2020 ◽  
Vol 15 ◽  
Author(s):  
Fatima Aerts-Kaya
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Ex Vivo ◽  
Stress Conditions ◽  
Stress Factors ◽  
Hematopoietic Stem ◽  
Induced Stress

: In contrast to their almost unlimited potential for expansion in vivo and despite years of dedicated research and optimization of expansion protocols, the expansion of Hematopoietic Stem Cells (HSCs) in vitro remains remarkably limited. Increased understanding of the mechanisms that are involved in maintenance, expansion and differentiation of HSCs will enable the development of better protocols for expansion of HSCs. This will allow procurement of HSCs with long-term engraftment potential and a better understanding of the effects of the external influences in and on the hematopoietic niche that may affect HSC function. During collection and culture of HSCs, the cells are exposed to suboptimal conditions that may induce different levels of stress and ultimately affect their self-renewal, differentiation and long-term engraftment potential. Some of these stress factors include normoxia, oxidative stress, extra-physiologic oxygen shock/stress (EPHOSS), endoplasmic reticulum (ER) stress, replicative stress, and stress related to DNA damage. Coping with these stress factors may help reduce the negative effects of cell culture on HSC potential, provide a better understanding of the true impact of certain treatments in the absence of confounding stress factors. This may facilitate the development of better ex vivo expansion protocols of HSCs with long-term engraftment potential without induction of stem cell exhaustion by cellular senescence or loss of cell viability. This review summarizes some of available strategies that may be used to protect HSCs from culture-induced stress conditions.

scholarly journals Exploring the Role of Mesenchymal Stem Cells During Normothermic Organ Perfusion: A New Paradigm to Enhance Outcome Following Allograft Transplantation

2018 ◽  
Vol 5 (1) ◽  
pp. 47-52
Author(s):  
Mohamed Morsy ◽  
Mohammad Ayaz Hossain ◽  
Atul Bagul
Keyword(s):  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Organ Transplantation ◽  
Ex Vivo ◽  
Solid Organ Transplantation ◽  
Short Review ◽  
Solid Organ ◽  
New Paradigm ◽  
Liver And Kidney

Background: Normothermic Machine Perfusion (NMP) has been established in the field of solid organ transplantation for both liver and kidney allografts. The ability to perfuse organs at body temperature enables viability assessment as well as optimisation prior to implantation. Discussion: A recent in vitro report of the use of Mesenchymal Stem Cells (MSCs) in the use of a normothermic lung perfusion circuit has raised the possibility of their use in solid organ transplantation. The aim of this short review is to outline the potential uses of bone marrow derived MSCs for their use in renal allograft ex vivo NMP. An overview is provided of current literature of NMP as well as theorised uses for MSCs.

scholarly journals Low Oxygen Tension Potentiates Proliferation and Stemness but Not Multilineage Differentiation of Caprine Male Germline Stem Cells

2021 ◽  
Author(s):  
Shiva Pratap Singh ◽  
Suresh Dinkar Kharche ◽  
Manisha Pathak ◽  
Ravi Ranjan ◽  
Yogesh Kumar Soni ◽  
...  
Keyword(s):  
Stem Cells ◽  
Ex Vivo ◽  
Growth Characteristics ◽  
Population Doubling ◽  
Population Doubling Time ◽  
Germline Stem Cells ◽  
Multilineage Differentiation ◽  
Low Oxygen ◽  
Differentiation Potential

Abstract The milieu of testicular germline stem cells (mGSCs) is characterized as low oxygen (O2) environment, whereas, there in-vitro expansion is typically performed under normoxia (20-21% O2). Here, we evaluated and compared the culture and multilineage differentiation characteristics of enriched (through differential platting and percoll density centrifugation) caprine mGSCs (cmGSCs) under hypoxic (5% O2) and normoxic (21% O2) culture conditions. For this, in addition to growth characteristics and population-doubling time (PDT); viability, proliferation, senescence, and expression of key-markers of adhesion (β-integrin and E-Cadherin) and stemness (OCT-4, THY-1 and UCHL-1) were evaluated and compared under normoxia and hypoxia. Moreover, the extent of multilineage differentiation (neurogenic, adipogenic, and chondrogenic differentiation) was assessed. The survival, viability and proliferation were significantly promoted and PDT was reduced (p < 0.05), thus yielding a higher number of viable cells with larger colonies under hypoxia. Furthermore, expression of stemness and adhesion markers was distinctly increased under lowered O2 condition. Conversely, the presence of differentiated regions and expression of differentiation specific key genes [C/EBPα (adipogenic), nestin and β-tubulin (neurogenic), and COL2A1 (chondrogenic)] were significantly (p < 0.05) reduced under hypoxic conditions. These data demonstrate that culturing cmGSCs under hypoxia augments the growth characteristics, and stemness but not the multilineage differentiation potential of cmGSCs as compared with normoxia. These data are important for the development of robust methodologies for ex-vivo expansion and lineage-committed differentiation of cmGSCs for clinical applications.

Human Anterior Lens Capsule as a Biologic Substrate for the Ex Vivo Expansion of Limbal Stem Cells in Ocular Surface Reconstruction

Cornea ◽  
2007 ◽  
Vol 26 (4) ◽  
pp. 473-478 ◽  
Author(s):  
Ahmed Galal ◽  
Juan J Perez-Santonja ◽  
Jose Luis Rodriguez-Prats ◽  
Marta Abad ◽  
Jorge Alio
Keyword(s):  
Stem Cells ◽  
Surface Reconstruction ◽  
Ocular Surface ◽  
Ex Vivo ◽  
Ex Vivo Expansion ◽  
Lens Capsule ◽  
Limbal Stem Cells ◽  
Ocular Surface Reconstruction ◽  
Anterior Lens Capsule

scholarly journals Dose-Independent Therapeutic Benefit of Bone Marrow Stem Cell Transplantation after MI in Mice

Biomedicines ◽  
2020 ◽  
Vol 8 (6) ◽  
pp. 157
Author(s):  
Nicole Zarniko ◽  
Anna Skorska ◽  
Gustav Steinhoff ◽  
Robert David ◽  
Ralf Gaebel
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Stem Cell ◽  
Stem Cell Transplantation ◽  
Cell Transplantation ◽  
Ex Vivo ◽  
Therapeutic Benefit ◽  
Dependent Manner ◽  
Mesenchymal Progenitors

Several cell populations derived from bone marrow (BM) have been shown to possess cardiac regenerative potential. Among these are freshly isolated CD133+ hematopoietic as well as culture-expanded mesenchymal stem cells. Alternatively, by purifying CD271+ cells from BM, mesenchymal progenitors can be enriched without an ex vivo cultivation. With regard to the limited available number of freshly isolated BM-derived stem cells, the effect of the dosage on the therapeutic efficiency is of particular interest. Therefore, in the present pre-clinical study, we investigated human BM-derived CD133+ and CD271+ stem cells for their cardiac regenerative potential three weeks post-myocardial infarction (MI) in a dose-dependent manner. The improvement of the hemodynamic function as well as cardiac remodeling showed no therapeutic difference after the transplantation of both 100,000 and 500,000 stem cells. Therefore, beneficial stem cell transplantation post-MI is widely independent of the cell dose and detrimental stem cell amplification in vitro can likely be avoided.

Long-Term Ex Vivo Maintenance and Expansion of Transplantable Human Hematopoietic Stem Cells

Blood ◽  
1999 ◽  
Vol 94 (5) ◽  
pp. 1623-1636 ◽  
Author(s):  
Chu-Chih Shih ◽  
Mickey C.-T. Hu ◽  
Jun Hu ◽  
Jeffrey Medeiros ◽  
Stephen J. Forman
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
In Vitro Culture ◽  
Culture System ◽  
Ex Vivo ◽  
Human Stem Cells ◽  
Hematopoietic Stem ◽  
In Vitro Culture System

Abstract We have developed a stromal-based in vitro culture system that facilitates ex vivo expansion of transplantable CD34+thy-1+ cells using long-term hematopoietic reconstitution in severe combined immunodeficient-human (SCID-hu) mice as an in vivo assay for transplantable human hematopoietic stem cells (HSCs). The addition of leukemia inhibitory factor (LIF) to purified CD34+ thy-1+ cells on AC6.21 stroma, a murine bone marrow–derived stromal cell line, caused expansion of cells with CD34+ thy-1+ phenotype. Addition of other cytokines, including interleukin-3 (IL-3), IL-6, granulocyte-macrophage colony-stimulating factor, and stem cell factor, to LIF in the cultures caused a 150-fold expansion of cells retaining the CD34+ thy-1+ phenotype. The ex vivo–expanded CD34+ thy-1+ cells gave rise to multilineage differentiation, including myeloid, T, and B cells, when transplanted into SCID-hu mice. Both murine LIF (cannot bind to human LIF receptor) and human LIF caused expansion of human CD34+ thy-1+ cells in vitro, suggesting action through the murine stroma. Furthermore, another human HSC candidate, CD34+ CD38− cells, shows a similar pattern of proliferative response. This suggests thatex vivo expansion of transplantable human stem cells under this in vitro culture system is a general phenomenon and not just specific for CD34+ thy-1+ cells.

Ex vivo treatment of proliferating human cord blood stem cells with stroma-derived factor–1 enhances their ability to engraft NOD/SCID mice

Blood ◽  
2002 ◽  
Vol 99 (9) ◽  
pp. 3454-3457 ◽  
Author(s):  
Hanno Glimm ◽  
Patrick Tang ◽  
Ian Clark-Lewis ◽  
Christof von Kalle ◽  
Connie Eaves
Keyword(s):  
Stem Cells ◽  
Cord Blood ◽  
Transforming Growth Factor ◽  
Ex Vivo ◽  
Severe Combined Immunodeficiency ◽  
Human Cord Blood ◽  
Hematopoietic Stem ◽  
Steel Factor ◽  
Tgf Β1

Abstract Ex vivo proliferation of hematopoietic stem cells (HSCs) is important for cellular and gene therapy but is limited by the observation that HSCs do not engraft as they transit S/G2/M. Recently identified candidate inhibitors of human HSC cycling are transforming growth factor-β1(TGF-β1) and stroma-derived factor–1 (SDF-1). To determine the ability of these factors to alter the transplantability of human HSCs proliferating in vitro, lin− cord blood cells were first cultured for 96 hours in serum-free medium containing Flt3 ligand, Steel factor, interleukin-3, interleukin-6, and granulocyte colony-stimulating factor. These cells were then transferred to medium containing Steel factor and thrombopoietin with or without SDF-1 and/or TGF-β1 for 48 hours. Exposure to SDF-1 but not TGF-β1 significantly increased (&gt; 2-fold) the recovery of HSCs able to repopulate nonobese diabetic/severe combined immunodeficiency mice. These results suggest new strategies for improving the engraftment activity of HSCs stimulated to proliferate ex vivo.

scholarly journals Recent Advances in the Design of Topical Ophthalmic Delivery Systems in the Treatment of Ocular Surface Inflammation and Their Biopharmaceutical Evaluation

Pharmaceutics ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 570 ◽  
Author(s):  
Roseline Mazet ◽  
Josias B. G. Yaméogo ◽  
Denis Wouessidjewe ◽  
Luc Choisnard ◽  
Annabelle Gèze
Keyword(s):  
Ocular Surface ◽  
Ex Vivo ◽  
Immunosuppressive Agents ◽  
Delivery Systems ◽  
Ocular Inflammation ◽  
Limiting Factors ◽  
Common Symptom ◽  
Eye Drops ◽  
Colloidal Systems

Ocular inflammation is one of the most common symptom of eye disorders and diseases. The therapeutic management of this inflammation must be rapid and effective in order to avoid deleterious effects for the eye and the vision. Steroidal (SAID) and non-steroidal (NSAID) anti-inflammatory drugs and immunosuppressive agents have been shown to be effective in treating inflammation of the ocular surface of the eye by topical administration. However, it is well established that the anatomical and physiological ocular barriers are limiting factors for drug penetration. In addition, such drugs are generally characterized by a very low aqueous solubility, resulting in low bioavailability as only 1% to 5% of the applied drug permeates the cornea. The present review gives an updated insight on the conventional formulations used in the treatment of ocular inflammation, i.e., ointments, eye drops, solutions, suspensions, gels, and emulsions, based on the commercial products available on the US, European, and French markets. Additionally, sophisticated formulations and innovative ocular drug delivery systems will be discussed. Promising results are presented with micro- and nanoparticulated systems, or combined strategies with polymers and colloidal systems, which offer a synergy in bioavailability and sustained release. Finally, different tools allowing the physical characterization of all these delivery systems, as well as in vitro, ex vivo, and in vivo evaluations, will be considered with regards to the safety, the tolerance, and the efficiency of the drug products.

Therapeutic Effect of HOXB4-Expanded Stem Cells in Mice with Beta Thalassemia Given a Non-Myeloablative Conditioning Regimen.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 341-341
Author(s):  
Silvia Bakovic ◽  
Patricia M. Rosten ◽  
Connie J. Eaves ◽  
R. Keith Humphries
Keyword(s):  
Stem Cells ◽  
Gene Therapy ◽  
Ex Vivo ◽  
Globin Gene ◽  
Conditioning Regimen ◽  
Beta Thalassemia ◽  
Mouse Bone Marrow ◽  
Myeloablative Conditioning ◽  
Hematopoietic Stem

Abstract The ultimate promise of gene therapy for patients with hemoglobinopathies depends on the development of safe strategies for achieving 2 goals. One is to obtain efficient and permanent correction of the gene defect in autologous hematopoietic stem cells (HSCs). The second is to develop methods for the pre-transplant amplification of transduced HSCs to high levels to ensure that they will outcompete the large residual endogenous HSC population remaining in non-myeloablated hosts (e.g. previous experiments have shown that a minimum of ~5 × 106 normal adult mouse bone marrow (BM) cells (~500 HSC) is required to achieve a level of chimerism of 20% in mice given 200 cGy). The ability of HOXB4 to promote HSC self-renewal divisions in short term culture prior to their use as transplants offers an attractive approach to achieve this latter goal. As a first test we transduced day-4 5FU BM cells from normal mice with a MSCV-HOXB4-IRES-GFP or control MSCV-IRES-GFP virus and then transplanted the cells either before or after 7 days maintenance in vitro into normal recipients given 250 cGy. Mice transplanted with an estimated 50 HSCs immediately after transduction with either virus reached equivalent low levels of chimerism (~10%) showing that HOXB4 does not impart an in vivo selective growth advantage under sublethal conditions. After ex vivo culture, the GFP transduced cells yielded an even lower level of chimerism (~5%), in contrast recipients of cultured HOXB4-transduced cells attained much higher stable levels of lympho-myeloid chimerism (~50%), indicative of a marked expansion of the HSCs pre-transplant and their retention of robust competitive repopulating potential. We then applied this approach to a gene therapy model of severe β-thalassemia in mice bearing a homozygous deletion of the β-major globin gene (β-MDD). To model a transplant of genetically corrected cells, BM cells were harvested from day-4 5FU pre-treated congenic wild-type donors and transduced with the HOXB4 virus. Cells were then cultured for 10 days and the progeny of 200K starting cells transplanted into 3 β-MDD and 4 normal recipients given 200 cGy. Transplantation of 500K freshly harvested day-4 5FU BM cells into 4 similarly conditioned control mice failed to produce significant chimerism (1–3% at 5 months). In contrast, all 4 control recipients of ex vivo expanded HOXB4-transduced cells exhibited significant stable chimerism (21±6% at 5 months). Similar levels of chimerism were also achieved in all 3 β-MDD recipients (18–76%), one of which was sustained at 34% at 5 months (52% in the RBCs). This was associated with substantial improvement in the Hct (36% vs 23% in untreated β-MDD), Hb (10.5 vs 5 g/dl) and RBC morphology. Southern blot analyses performed on 53 individual in vitro-expanded myeloid colonies generated from FACS-selected GFP+ marrow cells from this mouse 2 months post-transplant showed 19 distinct integration patterns indicating reconstitution from polyclonal expanded HSCs. This conclusion was further confirmed by proviral integration site analyses, which identified 13 separate integration sites from 9 colonies that had unique proviral patterns. These data demonstrate the curative potential of ex vivo expanded HSCs in a preclinical model of β-thalassemia treated with non-myeloablative conditioning. They also underscore the potential of HOXB4 as a potent tool to achieve the HSC expansions required.

Recreating a Human Hematopoietic Stem Cell Niche in Vitro by Unique Stroma Cells from the First Trimester Human Placenta and Fetal Liver

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 3568-3568
Author(s):  
Mattias Magnusson ◽  
Melissa Romero ◽  
Sacha Prashad ◽  
Ben Van Handel ◽  
Suvi Aivio ◽  
...  
Keyword(s):  
Stem Cells ◽  
Human Placenta ◽  
Ex Vivo ◽  
Fetal Liver ◽  
Embryonic Stem ◽  
Cell Types ◽  
First Trimester ◽  
Hematopoietic Stem ◽  
Human Hscs

Abstract Expansion of human hematopoietic stem cells (HSCs) ex vivo has been difficult due to limited understanding of their growth requirements and the molecular complexity of their natural microenvironments. To mimic the niches in which human HSCs normally develop and expand during ontogeny, we have derived two unique types of stromal niche cells from the first trimester human placenta and the fetal liver. These lines either support maintenance of multipotential progenitors in culture, or promote differentiation into macrophages. Impressively, the supportive lines facilitate over 50,000-fold expansion of the most immature human HSCs/progenitors (CD34+CD38-Thy1+) during 8-week culture supplemented with minimal cytokines FLT3L, SCF and TPO, whereas the cells cultured on non-supportive stroma or without stroma under the same conditions differentiated within 2 weeks. As the supportive stroma lines also facilitate differentiation of human hematopoietic progenitors into myeloid, erythroid and B-lymphoid lineages, we were able to show that the expanded progenitors preserved full multipotentiality during long-term culture ex vivo. Furthermore, our findings indicate that the supportive stroma lines also direct differentiation of human embryonic stem cells (hESC) into hematopoietic progenitor cells (CD45+CD34+) that generate multiple types of myeloerythroid colonies. These data imply that the unique supportive niche cells can both support hematopoietic specification and sustain a multilineage hematopoietic hierarchy in culture over several weeks. Strikingly, the supportive effect from the unique stromal cells was dominant over the differentiation effect from the non-supportive lines. Even supernatant from the supportive lines was able to partially protect the progenitors that were cultured on the non-supportive lines, whereas mixing of the two types of stroma resulted in sustained preservation of the multipotential progenitors. These results indicate that the supportive stroma cells possess both secreted and surface bound molecules that protect multipotentiality of HSCs. Global gene expression analysis revealed that the supportive stroma lines from both the placenta and the fetal liver were almost identical (r=0.99) and very different from the non-supportive lines that promote differentiation (r=0.34), implying that they represent two distinct niche cell types. Interestingly, the non-supportive lines express known mesenchymal markers such as (CD73, CD44 and CD166), whereas the identity of the supportive cells is less obvious. In summary, we have identified unique human stromal niche cells that may be critical components of the HSC niches in the placenta and the fetal liver. Molecular characterization of these stroma lines may enable us to define key mechanisms that govern the multipotentiality of HSCs.

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