Role of glioma stem cells in promoting tumor chemo- and radioresistance: A systematic review of potential targeted treatments

BACKGROUND Gliomas pose a significant challenge to effective treatment despite advancements in chemotherapy and radiotherapy.Glioma stem cells(GSCs),a subset within tumors,contribute to resistance,tumor heterogeneity,and plasticity.Recent studies reveal GSCs’role in therapeutic resistance,driven by DNA repair mechanisms and dynamic transitions between cellular states.Resistance mechanisms can involve different cellular pathways,most of which have been recently reported in the literature.Despite progress,targeted therapeutic approaches lack consensus due to GSCs’high plasticity.AIM To analyze targeted therapies against GSC-mediated resistance to radio-and chemotherapy in gliomas,focusing on underlying mechanisms.METHODS A systematic search was conducted across major medical databases(PubMed,Embase,and Cochrane Library)up to September 30,2023.The search strategy utilized relevant Medical Subject Heading terms and keywords related to including“glioma stem cells”,“radiotherapy”,“chemotherapy”,“resistance”,and“targeted therapies”.Studies included in this review were publications focusing on targeted therapies against the molecular mechanism of GSC-mediated re-sistance to radiotherapy resistance(RTR).RESULTS In a comprehensive review of 66 studies on stem cell therapies for SCI,452 papers were initially identified,with 203 chosen for full-text analysis.Among them,201 were deemed eligible after excluding 168 for various reasons.The temporal breakdown of studies illustrates this trend:2005-2010(33.3%),2011-2015(36.4%),and 2016-2022(30.3%).Key GSC models,particularly U87(33.3%),U251(15.2%),and T98G(15.2%),emerge as significant in research,reflecting their representativeness of glioma characteristics.Pathway analysis indicates a focus on phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin(mTOR)(27.3%)and Notch(12.1%)pathways,suggesting their crucial roles in resistance development.Targeted molecules with mTOR(18.2%),CHK1/2(15.2%),and ATP binding cassette G2(12.1%)as frequent targets underscore their importance in overcoming GSC-mediated resistance.Various therapeutic agents,notably RNA inhibitor/short hairpin RNA(27.3%),inhibitors(e.g.,LY294002,NVP-BEZ235)(24.2%),and monoclonal antibodies(e.g.,cetuximab)(9.1%),demonstrate versatility in targeted therapies.among 20 studies(60.6%),the most common effect on the chemotherapy resistance response is a reduction in temozolomide resistance(51.5%),followed by reductions in carmustine resistance(9.1%)and doxorubicin resistance(3.0%),while resistance to RTR is reduced in 42.4%of studies.CONCLUSION GSCs play a complex role in mediating radioresistance and chemoresistance,emphasizing the necessity for precision therapies that consider the heterogeneity within the GSC population and the dynamic tumor microenvironment to enhance outcomes for glioblastoma patients.

Treatment for paraganglioma with stereotactic radiotherapy

BACKGROUND Paragangliomas(PG)are rare neoplasms of neuroendocrine origin that tend to be highly vascularized,slow-growing,and usually sporadic.To date,common treatment options are surgical resection(SR),with or without radiation therapy(RT),and a watch-and-wait approach.AIM To evaluate the local control and effectiveness of exclusive fractionated stereotactic RT(FSRT)treatment in unresectable PG(uPG).METHODS We retrospectively evaluated patients with uPG(medically inoperable or refused SR)treated with FSRT with a Cyberknife System(Accuray Incorporated,Sunnyvale,California).Toxicity and initial efficacy were evaluated.RESULTS From May 2009 to January 2023,6 patients with a median age of 68(range 20-84)were treated with FSRT.The median delivered dose was 21 Gy(range 20-30 Gy)at a median isodose line of 75.5%(range 70%-76%)in 4 fractions(range 3-5 fractions).The median volume was 13.6 mL(range 12.4-65.24 mL).The median cumulative biological effective dose and equivalent dose in 2-Gy fractions were 70 Gy and 37.10 Gy respectively.Site of origin involved were the timpa-nojugular glomus(4/6),temporal bone,and cervical spine.In 1 of the 6 patients,the follow-up was insufficient;5 of 6 patients showed a 5-year overall survival and 5-year progression-free survival of 100%.We observed negligible toxicities during and after RT.The majority of patients showed stable symptoms during follow-up.Only 1 patient developed spine metastases.CONCLUSION Our preliminary results on this small cohort of patients suggest that FSRT could be an effective and safe alternative to SR.

Current status and future perspectives on stem cell transplantation for spinal cord injury

BACKGROUND Previous assessments of stem cell therapy for spinal cord injuries(SCI)have encountered challenges and constraints.Current research primarily emphasizes safety in early-phase clinical trials,while systematic reviews prioritize effectiveness,often overlooking safety and translational feasibility.This situation prompts inquiries regarding the readiness for clinical adoption.AIM To offer an up-to-date systematic literature review of clinical trial results concerning stem cell therapy for SCI.METHODS A systematic search was conducted across major medical databases[PubMed,Embase,Reference Citation Analysis(RCA),and Cochrane Library]up to October 14,2023.The search strategy utilized relevant Medical Subject Heading(MeSH)terms and keywords related to"spinal cord","injury","clinical trials","stem cells","functional outcomes",and"adverse events".Studies included in this review consisted of randomized controlled trials and non-randomized controlled trials reporting on the use of stem cell therapies for the treatment of SCI.RESULTS In a comprehensive review of 66 studies on stem cell therapies for SCI,496 papers were initially identified,with 237 chosen for full-text analysis.Among them,236 were deemed eligible after excluding 170 for various reasons.These studies encompassed 1086 patients with varying SCI levels,with cervical injuries being the most common(42.2%).Bone marrow stem cells were the predominant stem cell type used(71.1%),with various administration methods.Follow-up durations averaged around 84.4 months.The 32.7%of patients showed functional improvement from American spinal injury association Impairment Scale(AIS)A to B,40.8%from AIS A to C,5.3%from AIS A to D,and 2.1%from AIS B to C.Sensory improvements were observed in 30.9%of patients.A relatively small number of adverse events were recorded,including fever(15.1%),headaches(4.3%),muscle tension(3.1%),and dizziness(2.6%),highlighting the potential for SCI recovery with stem cell therapy.CONCLUSION In the realm of SCI treatment,stem cell-based therapies show promise,but clinical trials reveal potential adverse events and limitations,underscoring the need for meticulous optimization of transplantation conditions and parameters,caution against swift clinical implementation,a deeper understanding of SCI pathophysiology,and addressing ethical,tumorigenicity,immunogenicity,and immunotoxicity concerns before gradual and careful adoption in clinical practice.

Role of stem cells-based in facial nerve reanimation:A meta-analysis of histological and neurophysiological outcomes

BACKGROUND Treatments involving stem cell(SC)usage represent novel and potentially interesting alternatives in facial nerve reanimation.Current literature includes the use of SC in animal model studies to promote graft survival by enhancing nerve fiber growth,spreading,myelinization,in addition to limiting fibrotic degeneration after surgery.However,the effectiveness of the clinical use of SC in facial nerve reanimation has not been clarified yet.AIM To investigate the histological,neurophysiological,and functional outcomes in facial reanimation using SC,compared to autograft.METHODS Our study is a systematic review of the literature,consistently conducted according to the preferred reporting items for systematic reviews and meta-analyses statement guidelines.The review question was:In facial nerve reanimation on rats,has the use of stem cells revealed as effective when compared to autograft,in terms of histological,neurophysiological,and functional outcomes?Random-effect meta-analysis was conducted on histological and neurophysiological data from the included comparative studies.RESULTS After screening 148 manuscript,five papers were included in our study.43 subjects were included in the SC group,while 40 in the autograft group.The meta-analysis showed no significative differences between the two groups in terms of myelin thickness[CI:-0.10(-0.20,0.00);I^(2)=29%;P=0.06],nerve fibers diameter[CI:0.72(-0.93,3.36);I^(2)=72%;P=0.6],compound muscle action potential amplitude[CI:1.59(0.59,3.77);I^(2)=89%;P=0.15]and latency[CI:0.66(-1.01,2.32);I^(2)=67%;P=0.44].The mean axonal diameter was higher in the autograft group[CI:0.94(0.60,1.27);I^(2)=0%;P≤0.001].CONCLUSION The role of stem cells in facial reanimation is still relatively poorly studied,in animal models,and available results should not discourage their use in future studies on human subjects.