Genetically engineered human mesenchymal stem cells produce met-enkephalin at augmented higher levels in vitro

Mesenchymal stem cells from bone marrow attenuated the chronic morphine-induced cAMP accumulation in vitro

Even though opioid tolerance is both a common and a major challenge in medicine, treatment with opioids is currently the primary method used to treat acute and chronic pain. The cAMP accumulation induced by chronic morphine is regarded as one of the molecular mechanisms leading to its tolerance and dependence characteristics. In the present study, we differentiated SH-SY5Y cells into neuron-like cells by retinoic acid (RA), pretreated these cells with morphine, and tested their cAMP levels under different conditions, including co-culture with bone marrow-derived human mesenchymal stem cells from bone marrow (hMSCs-BM) at various hMSCs-BM/SH-SY5Y ratios (1:5, 1:25, and 1:125), by direct cell-to-cell contact or without cell-to-cell contact, and by conditioned medium (CM) from hMSCs-BM. We found that chronic treatment with 10 μM morphine led to cAMP upregulation in those RA-differentiated SH-SY5Y cells while the morphine induced-cAMP accumulation was significantly attenuated by co-culturing with hMSCs-BM by direct cell-to-cell contact at a lower cell ratio (1:25) and a higher cell ratio (1:5). However, at neither the low or higher cell ratios could hMSCs-BM inhibit morphine-induced cAMP accumulation in RA-differentiated SH-SY5Y cells without cell-to-cell contact. In summary, hMSCs-BM can successfully inhibit morphine-induced cAMP up-regulation in RA-differentiated SH-SY5Y cells by cell-to-cell contact at a higher ratio, suggesting that hMSCs-BM may serve as valuable therapeutics to minimize the risk of drug abuse and addiction in the treatment of morphine tolerance and dependence.

Intrathecal administration of human bone marrow mesenchymal stem cells genetically modified with human proenkephalin gene decrease nociceptive pain in neuropathic rats

Background

Mesenchymal stem cell (MSC) has been one of the potential tools in neuropathic pain therapy; however, the augmented efficacy may be expected when they are modified with human proenkephalin (hPPE) gene. In the current study, the antinociceptive effect of human bone marrow stem cells (hBMSCs) engineered with hPPE gene (hPPE-hBMSCs) on sciatic nerve chronic constriction injury (CCI)-induced neuropathic pain in rats was investigated.

Methods

Primary-cultured hBMSCs were passaged and modified with hPPE, and the cell suspensions (6 × 10⁶) were then intrathecally injected into a rat model of CCI. Paw mechanical withdrawal threshold and paw withdrawal thermal latency were measured before and after CCI surgery. The effects of hPPE gene transfer on hBMSCs bioactivity were analyzed in vitro and in vivo.

Results

No changes were observed in the surface phenotypes and differentiation of hBMSCs after gene transfer. The hPPE-hBMSC group showed improved paw mechanical withdrawal threshold and paw thermal withdrawal latency values on the ipsilateral side of rats with CCI from day 9 post-surgery, and the analgesic effect was reversed by naloxone. Leucine-enkephalin (L-EK) secretion was augmented in the hPPE-engineered hBMSC group.

Conclusions

The intrathecal administration of BMSCs modified with hPPE gene can effectively relieve pain caused by chronic constriction injury in rats and might be a potentially therapeutic tool for neuropathic pain in humans.

Article Commentary: Stem Cell Research in Cell Transplantation: An Analysis of Geopolitical Influence by Publications

One of the fastest growing fields in researching treatments for neurodegenerative and other disorders is the use of stem cells. These cells are naturally occurring and can be obtained from three different stages of an organism's life: embryonic, fetal, and adult. In the US, political doctrine has restricted use of federal funds for stem cells, enhancing research towards an adult source. In order to determine how this legislation may be represented by the stem cell field, a retrospective analysis of stem cell articles published in the journal Cell Transplantation over a 2-year period was performed. Cell Transplantation is considered a translational journal from preclinical to clinical, so it was of interest to determine the publication outcome of stem cell articles 6 years after the US regulations. The distribution of the source of stem cells was found to be biased towards the adult stage, but relatively similar over the embryonic and fetal stages. The fetal stem cell reports were primarily neural in origin, whereas the adult stem cell ones were predominantly mesenchymal and used mainly in neural studies. The majority of stem cell studies published in Cell Transplantation were found to fall under the umbrella of neuroscience research. American scientists published the most articles using stem cells with a bias towards adult stem cells, supporting the effect of the legislation, whereas Europe was the leading continent with a bias towards embryonic and fetal stem cells, where research is “controlled” but not restricted. Japan was also a major player in the use of stem cells. Allogeneic transplants (where donor and recipient are the same species) were the most common transplants recorded, although the transplantation of human-derived stem cells into rodents was the most common specific transplantation performed. This demonstrates that the use of stem cells is an increasingly important field (with a doubling of papers between 2005 and 2006), which is likely to develop into a major therapeutic area over the next few decades and that funding restrictions can affect the type of research being performed.

Targeted cell reprogramming produces analgesic chromaffin-like cells from human mesenchymal stem cells

Transplantation of allogeneic adrenal chromaffin cells demonstrated the promise of favorable outcomes for pain relief in patients. However, there is a very limited availability of suitable human adrenal gland tissues, genetically well-matched donors in particular, to serve as grafts. Xenogeneic materials, such as porcine and bovine adrenal chromaffin cells, present problems; for instance, immune rejection and possible pathogenic contamination are potential issues. To overcome these challenges, we have tested the novel approach of cell reprogramming to reprogram human bone marrow (BM)-derived mesenchymal stem cells (hMSCs) using cellular extracts of porcine chromaffin cells. We produced a new type of cell, chromaffin-like cells, generated from the reprogrammed hMSCs, which displayed a significant increase in expression of human preproenkephalin (hPPE), a precursor for enkephalin opioid peptides, compared to the inherent expression of hPPE in naive hMSCs. The resultant chromaffin-like cells not only expressed the key molecular markers of adrenal chromaffin cells, such as tyrosine hydroxylase (TH) and methionine enkephalin (Met-enkephalin), but also secreted opioid peptide Met-enkephalin in culture. In addition, intrathecal injection of chromaffin-like cells in rats produced significant analgesic effects without using immunosuppressants. These results suggest that analgesic chromaffin-like cells can be produced from an individual's own tissue-derived stem cells by targeted cell reprogramming and also that these chromaffin-like cells may serve as potential autografts for chronic pain management.

Generation of neural stem cell-like cells from bone marrow-derived human mesenchymal stem cells

Under appropriate culture conditions, bone marrow (BM)-derived mesenchymal stem cells are capable of differentiating into diverse cell types unrelated to their phenotypical embryonic origin, including neural cells. Here, we report the successful generation of neural stem cell (NSC)-like cells from BM-derived human mesenchymal stem cells (hMSCs). Initially, hMSCs were cultivated in a conditioned medium of human neural stem cells. In this culture system, hMSCs were induced to become NSC-like cells, which proliferate in neurosphere-like structures and express early NSC markers. Like central nervous system-derived NSCs, these BM-derived NSC-like cells were able to differentiate into cells expressing neural markers for neurons, astrocytes, and oligodendrocytes. Whole-cell patch clamp recording revealed that neuron-like cells, differentiated from NSC-like cells, exhibited electrophysiological properties of neurons, including action potentials. Transplantation of NSC-like cells into mouse brain confirmed that these NSC-like cells retained their capability to differentiate into neuronal and glial cells in vivo. Our data show that multipotent NSC-like cells can be efficiently produced from BM-derived hMSCs in culture and that these cells may serve as a useful alternative to human neural stem cells for potential clinical applications such as autologous neuroreplacement therapies.

Cell based therapy for the management of chronic pain

The management of chronic pain, particularly neuropathic pain, still has significant unmet needs. In addition to inadequate symptomatic relief, there are concerns about adverse effects and addiction associated with treatments. The transplantation of cells that secrete neuroactive substances with analgesic properties into the central nervous system has only become of practical interest in more recent years, but provides a novel strategy to challenge current approaches in treating chronic pain. This review covers pre-clinical and clinical studies from both allogeneic and xenogeneic sources for management of chronic refractory pain.

Intrathecal implantation of microencapsulated PC12 cells reduces cold allodynia in a rat model of neuropathic pain

The transplantation of cells into the central nervous system provides a constant and replenishable source of analgesic substances for the alleviation of chronic pain. In the present study, PC12 cells were microencapsulated in a semipermeable membrane that protected the cells from the host's immune system. A chronic neuropathic pain model was induced by chronic constriction injury (CCI) of the sciatic nerve in rats. Thirty Sprague-Dawley rats with CCI were divided randomly into two groups: the cell-loaded group received microencapsulated PC12 cells (n = 15) and the control group received empty capsules (n = 15). The microcapsules were implanted into the lumbar subarachnoid space. After implantation, a significant reduction of cold allodynia was observed in the rats of the cell-loaded group at 7, 14, 21, and 28 days compared to the control group with the empty capsules (P < 0.05). Furthermore, the levels of catecholamines and met-enkephalin in the cerebrospinal fluid of rats in the cell-loaded group were higher than the levels in the controls (P < 0.05). These results suggest that intrathecal microencapsulated PC12 cells could be a useful method for chronic neuropathic pain management.

Cell therapy for pain

BACKGROUND

Management of chronic pain remains a challenge in spite of numerous drugs that are either approved or still in development. Apart from inadequate relief, there are concerns about adverse effects and addiction. Cell therapy is being explored for relief of pain.

OBJECTIVE

To address the rationale for cell therapy for treatment of pain and its advantages over conventional pharmaceuticals. The prospects of translation of these techniques from experimental animals to clinical use are discussed.

METHODS

This review is based on the literature on cell therapy in relation to pain and is confined to experimental work as there are no approved therapies in this category.

RESULTS/CONCLUSIONS

A number of promising cell therapy technologies have been identified. These provide targeted approaches to delivery of antinociceptive molecules, avoiding subjecting the patient to systemic toxicity of drugs. There has been considerable progress in treating degenerative joint diseases causing pain. Management of neuropathic pain is a challenge and a number of ongoing studies are addressing it. Overall the future of cell therapy for pain is promising.

Sustained Analgesic Peptide Secretion and Cell Labeling Using a Novel Genetic Modification

Cell-based therapy for neuropathic pain could provide analgesics to local pain modulatory regions in a sustained, renewable fashion. In order to provide enhanced analgesic efficacy, transplantable cells may be engineered to produce complementary or increased levels of analgesic peptides. In addition, genetic labeling of modified cells is desirable for identification and tracking, but it should be retained intracellularly as desired analgesic peptides are secreted. Usually constructs encode proteins destined for either extra- or intracellular compartments, as these pathways do not cross. However, interactions between intracellular destinations provide a window of opportunity to overcome this limitation. In this report, we have explored this approach using a potential supplementary analgesic peptide, [Ser1]-histogranin (SHG), the stable synthetic derivative of a naturally occurring peptide with N-methyl D-aspartate (NMDA) antagonistic properties. A synthetic SHG gene was combined with (i) nerve growth factor-β (NGF-β) amino-terminal signal peptide to enable secretion, and (ii) a fluorescent cellular label (mRFP) with intervening cathepsin L cleavage site, and subcloned into a lentiviral vector. In addition, an endoplasmic retention signal, KDEL, was added to enable retrieval of mRFP. Using immunocytochemistry and confocal microscopic profile analysis, cells transduced by such lentiviruses were shown to synthesize a single SHG-mRFP polypeptide that was processed, targeted to expected subcellular destinations in several cell types. Dot blot and Western analysis revealed stable transduction and long-term secretion of SHG from PC12 cells in vitro. Transplantation of such cells provided modest analgesia in a rodent pain model consistent with low levels of SHG peptide in the cerebrospinal fluid (CSF). These results suggest that it is possible to deliver proteins with different final destinations from a single construct, such as pharmacologically active peptide for secretion and intracellular label for identifying transplantable cells.

Phenotypic characteristics of hybrid cells produced by cell fusion of porcine adrenal chromaffin cells with human mesenchymal stem cells: a preliminary study

BACKGROUND AND PURPOSE

Transplantation of adrenal chromaffin cells (CCs) that release endogenous opioid peptides and catecholamines produces significant antinociceptive effects in patients with terminal cancer pain. In clinical practice, however, obtaining a sufficient number of chromaffin cells may not be possible because of the limited availability of human adrenal tissue. Recent works have shown that fusion of bone marrow-derived cells with differentiated cells can occur spontaneously in vivo and acquire the phenotype of the recipient cells. In this study, we investigated the possibility of producing chromaffin-like cells by fusing human bone marrow-derived mesenchymal stem cells (MeSCs) with post-mitotic porcine CCs in vitro with the application of polyethylene glycol (PEG).

METHODS AND RESULTS

Before cell-to-cell fusion was initiated, MeSCs and CCs were labeled by fluorescence dyes DiO (green) and Dil (red), respectively. The hybrid cells generated by PEG-mediated fusion expressed a DiO and Dil double-staining with estimated fusion efficiency at approximately 40% of the total cell population. Further immunocytochemical examination for tyrosine hydroxylase and methionine enkephalin (markers for CCs) demonstrated positive immuno-reactivity in these hybrid cells 2 weeks post-fusion. More interestingly, some of the hybrid cells showed bromodeoxyuridine (BrdU)-positive immunostaining in the nuclei.

DISCUSSION

Our results show that these hybrid cells fused by CCs and MeSCs express some characteristics of the CC phenotype. A subpopulation of these hybrid cells are dividing cells with positive BrdU immunostaining, suggesting that a novel cellular production could be developed by a "reprogramming" mechanism through the application of targeted cell fusion strategies.

Endogenous opiates and behavior: 2006

This paper is the 29th consecutive installment of the annual review of research concerning the endogenous opioid system, now spanning 30 years of research. It summarizes papers published during 2006 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurological disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17).