Characteristics and outcomes of peripheral neuropathic pain patients with repeated applications of high-concentration capsaicin cutaneous patch: Results of a retrospective chart review in Germany.

OBJECTIVE: The aim of this study was to evaluate patient characteristics, concomitant analgesic medication, and pain intensity in a real-world setting in Germany, focusing on the repeated application of high-concentration capsaicin patch (HCCP) for neuropathic pain. DESIGN: Data were collected from electronic medical records of patients who received at least two HCCP treatments between January 2011 and July 2022. Subgroup analyses were performed based on the number of HCCP treatments, age groups, and specific neuropathic pain conditions. SETTING: The study was conducted at an outpatient pain center in Wiesbaden, Germany. SUBJECTS: The study included 97 patients, primarily diagnosed with neuropathic back pain, postoperative or post-traumatic neuropathic pain, and postherpetic neuralgia. METHODS: The daily dose of concomitant medications (eg, opioids and anticonvulsants) at the start of capsaicin therapy was compared with the average within 2 years of capsaicin therapy. The last observation carried forward method was used if HCCP treatment was discontinued before the end of the 2-year period. RESULTS: The majority of patients received concomitant medications, with opioids, anticonvulsants, and antidepressants being the most common. The average daily morphine equivalent dose decreased significantly during HCCP treatment. Pain intensity at baseline was generally high, but substantial improvements were observed in patients who received at least three HCCP applications. CONCLUSIONS: This study provides evidence for the effectiveness of HCCP treatment in reducing pain intensity and concomitant opioid use in patients with neuropathic pain. Further research is needed to explore the long-term outcomes and optimal treatment regimens for different patient populations.

Chemotherapy-induced peripheral neuropathy (CIPN): current therapies and topical treatment option with high-concentration capsaicin.

Cancer diagnosis and treatment are drastic events for patients and their families. Besides psychological aspects of the disease, patients are often affected by severe side effects related to the cancer itself or as a result of therapeutic interventions. Particularly, chemotherapy-induced peripheral neuropathy (CIPN) is the most prevalent neurological complication of oral or intravenous chemotherapy. The disorder may require dose reduction of chemotherapy and is accompanied by multiple symptoms with long-term functional impairment affecting quality of life (QoL), e.g., sensory and functional deteriorations as well as severe pain. Although CIPN may reverse or improve after termination of the causative chemotherapy, approximately 30-40% of patients are faced with chronicity of the symptoms. Due to the advantages in cancer diagnosis and treatments, survival rates of cancer patients rise and CIPN may occur even more frequently in the future. In this review, we summarize current recommendations of leading national and international societies regarding prevention and treatment options in CIPN. A special focus will be placed on current evidence for topical treatment of CIPN with high-dose capsaicin. Finally, an algorithm for CIPN treatment in clinical practice is provided, including both pharmacologic and non-pharmacologic modalities based on the clinical presentation.

Pluripotent stem cell-derived radial glia-like cells as stable intermediate for efficient generation of human oligodendrocytes.

Neural precursor cells (NPCs) derived from human pluripotent stem cells (hPSCs) represent an attractive tool for the in vitro generation of various neural cell types. However, the developmentally early NPCs emerging during hPSC differentiation typically show a strong propensity for neuronal differentiation, with more limited potential for generating astrocytes and, in particular, for generating oligodendrocytes. This phenomenon corresponds well to the consecutive and protracted generation of neurons and GLIA during normal human development. To obtain a more gliogenic NPC type, we combined growth factor-mediated expansion with pre-exposure to the differentiation-inducing agent retinoic acid and subsequent immunoisolation of CD133-positive cells. This protocol yields an adherent and self-renewing population of hindbrain/spinal cord radial glia (RG)-like neural precursor cells (RGL-NPCs) expressing typical neural stem cell markers such as nestin, ASCL1, SOX2, and PAX6 as well as RG markers BLBP, GLAST, vimentin, and GFAP. While RGL-NPCs maintain the ability for tripotential differentiation into neurons, astrocytes, and oligodendrocytes, they exhibit greatly enhanced propensity for oligodendrocyte generation. Under defined differentiation conditions promoting the expression of the major oligodendrocyte fate-determinants OLIG1/2, NKX6.2, NKX2.2, and SOX10, RGL-NPCs efficiently convert into NG2-positive oligodendroglial progenitor cells (OPCs) and are subsequently capable of in vivo myelination. Representing a stable intermediate between PSCs and OPCs, RGL-NPCs expedite the generation of PSC-derived oligodendrocytes with O4-, 4860-, and myelin basic protein (MBP)-positive cells that already appear within 7 weeks following growth factor withdrawal-induced differentiation. Thus, RGL-NPCs may serve as robust tool for time-efficient generation of human oligodendrocytes from embryonic and induced pluripotent stem cells.

Targeting the cytosolic innate immune receptors RIG-I and MDA5 effectively counteracts cancer cell heterogeneity in glioblastoma.

Cellular heterogeneity, for example, the intratumoral coexistence of cancer cells with and without stem cell characteristics, represents a potential root of therapeutic resistance and a significant challenge for modern drug development in glioblastoma (GBM). We propose here that activation of the innate immune system by stimulation of innate immune receptors involved in antiviral and antitumor responses can similarly target different malignant populations of glioma cells. We used short-term expanded patient-specific primary human GBM cells to study the stimulation of the cytosolic nucleic acid receptors melanoma differentiation-associated gene 5 (MDA5) and retinoic acid-inducible gene I (RIG-I). Specifically, we analyzed cells from the tumor core versus "residual GBM cells" derived from the tumor resection margin as well as stem cell-enriched primary cultures versus specimens without stem cell properties. A portfolio of human, nontumor neural cells was used as a control for these studies. The expression of RIG-I and MDA5 could be induced in all of these cells. Receptor stimulation with their respective ligands, p(I:C) and 3pRNA, led to in vitro evidence for an effective activation of the innate immune system. Most intriguingly, all investigated cancer cell populations additionally responded with a pronounced induction of apoptotic signaling cascades revealing a second, direct mechanism of antitumor activity. By contrast, p(I:C) and 3pRNA induced only little toxicity in human nonmalignant neural cells. Granted that the challenge of effective central nervous system (CNS) delivery can be overcome, targeting of RIG-I and MDA5 could thus become a quintessential strategy to encounter heterogeneous cancers in the sophisticated environments of the brain.

Direct conversion of fibroblasts into stably expandable neural stem cells.

Recent advances have suggested that direct induction of neural stem cells (NSCs) could provide an alternative to derivation from somatic tissues or pluripotent cells. Here we show direct derivation of stably expandable NSCs from mouse fibroblasts through a curtailed version of reprogramming to pluripotency. By constitutively inducing Sox2, Klf4, and c-Myc while strictly limiting Oct4 activity to the initial phase of reprogramming, we generated neurosphere-like colonies that could be expanded for more than 50 passages and do not depend on sustained expression of the reprogramming factors. These induced neural stem cells (iNSCs) uniformly display morphological and molecular features of NSCs, such as the expression of Nestin, Pax6, and Olig2, and have a genome-wide transcriptional profile similar to that of brain-derived NSCs. Moreover, iNSCs can differentiate into neurons, astrocytes, and oligodendrocytes. Our results demonstrate that functional NSCs can be generated from somatic cells by factor-driven induction.

Transcription factor-based modulation of neural stem cell differentiation using direct protein transduction.

In contrast to conventional gene transfer strategies, the direct introduction of recombinant proteins into cells bypasses the risk of insertional mutagenesis and offers an alternative to genetic intervention. Here, we explore whether protein transduction of the gliogenic transcription factor Nkx2.2 can be used to promote oligodendroglial differentiation of mouse embryonic stem cell (ESC)-derived neural stem cells (NSC). To that end, a recombinant cell-permeant form of Nkx2.2 protein was generated. Exposure of ESC-derived NSC to the recombinant protein and initiation of differentiation resulted in a two-fold increase in the number of oligodendrocytes. Furthermore, Nkx2.2-transduced cells exhibited a more mature oligodendroglial phenotype. Comparative viral gene transfer studies showed that the biological effect of Nkx2.2 protein transduction is comparable to that obtained by lentiviral transduction. The results of this proof-of-concept study depict direct intracellular delivery of transcription factors as alternative modality to control lineage differentiation in NSC cultures without genetic modification.