Masahiko Okuma

Transplantation of mesenchymal stem cells embedded in Atelocollagen® gel to the intervertebral disc: a potential therapeutic model for disc degeneration

Intervertebral disc degeneration is considered to be one of the major causes of low back pain. Despite this irreversible phenomenon, attempts to decelerate disc degeneration using various techniques have been reported. However, to date there has been no proven technique effective for broad clinical application. Based on previous studies, we hypothesize that maintenance of proteoglycan content in the disc is achieved by avoiding the depletion of nucleus pulposus and preserving the structure of the annulus is a primary factor in decelerating disc degeneration. One novel approach to solve the dilemma of intervertebral disc degeneration is found at the stem cell level. Mesenchymal stem cells (MSCs) are known to possess the ability to differentiate into various kinds of cells from mesenchymal origin. Although the majority of cells that contribute to disc formation are known to obtain chondrocyte-like phenotypes, no reported study has emphasized the correlation with mesenchymal stem cells. To evaluate the possible potential of MSCs in disc cell research and treatment of degenerative disc disease, autologous MSCs embedded in Atelocollagen gel were transplanted into the discs of rabbits which had undergone a procedure proven to induce degeneration. The results suggest that MSC transplantation is effective in decelerating disc degeneration in experimental models and provided new hopes for treatment of degenerative disc disease in humans. Atelocollagen gel served as an important carrier of MSCs in transplantation, permitting proliferation, matrix synthesis and differentiation of MSCs. This study strengthens the viable efficacy of practical application of MSCs in treatment of intervertebral disc disease.

Nucleus pulposus allograft retards intervertebral disc degeneration

Autogenous implantation of nucleus pulposus or nucleus pulposus cells that were activated by coculture retards intervertebral disc degeneration, but harvesting such grafts causes disc degeneration at the donor site. This study examined whether nucleus pulposus allografts similarly retard disc degeneration and whether such allografting induces immunologic rejection. Japanese White rabbits served as donors and recipients for allografts. Lumbar disc degeneration was induced by aspirating the nucleus pulposus. Two weeks later, intact nucleus pulposus or nucleus pulposus cells were injected and compared with a sham procedure and normal control. The recipients’ discs were examined histologically and immunologically at intervals for 16 weeks. Discs receiving an intact nucleus pulposus showed the least degeneration, followed by discs receiving nucleus pulposus cells, both of which were better than no treatment. These findings correlated directly with the intensity of immunochemical staining for Type II collagen. Allogeneic grafts did not induce any appreciable host-versus-graft response. Injection of nucleus pulposus and nucleus pulposus cells retards intervertebral disc degeneration. However, injection of intact nucleus pulposus is more effective than injection of nucleus pulposus cells alone. The intercellular matrix plays an important, but poorly understood, role in preserving intervertebral discs.

Effect of Reinsertion of Activated Nucleus Pulposus on Disc Degeneration: An Experimental Study on Various Types of Collagen in Degenerative Discs

We examined the emergence and sequential changes in type I, II, and VI collagen production in an experimental rabbit model of disc degeneration. Type I collagen was minimally present initially and did not change over 24 weeks. Type I collagen seemed to have no effect on the degenerative process in this model. Staining for type II collagen was positive circumferentially in chondrocytelike cells and was mild in the early phase of disc degeneration, when the chondrocytelike cells began to appear in the inner layers of the annulus fibrosus. The stain became stronger during the middle phase when the chondrocytelike cells arranged themselves in cluster. Compared with type II collagen, the staining for type VI collagen was relatively strong early in the degenerative process. These findings led us to speculate that these chondrocytelike cells play an active role in the degenerative process. The reinsertion of nucleus pulposus cells cocultured with annulus fibrosus delayed disc degeneration and the emergence of chondrocytelike cells. Considering that the emergence of chondrocytelike cells which produce type II and type VI collagen is delayed in discs with the injection of cocultured nucleus pulposus cells by annulus fibrosus cells, we conclude that chondrocytelike cells that produce type VI collagen also seems to accelerate degeneration. Type VI collagen is produced at an earlier phase than type II collagen and may be both active agent and a marker for disc degeneration.

Inhibitory effect of natural and environmental estrogens on thymic hormone production in thymus epithelial cell culture

The present study was carried out to assess the direct effect of natural estrogen and environmental estrogens on thymus epithelial cell (TEC) production/secretion of the thymic hormone thymosin-alpha 1 by using the technique of quantitative high-performance liquid chromatography. The presence of estrogen receptors in the TECs was also investigated. Murine TECs were cultured in the experimental DMEM medium containing various concentrations of natural or environmental estrogens, which was followed by determining the production of thymosin-alpha 1. The production of thymosin-alpha 1 by TECs was significantly inhibited by increasing concentrations of 17beta-estradiol (natural estrogen) over 3 x 10(-11) M, genistein (phytoestrogen) over 3 x 10(-9) M, coumestrol (phytoestrogen) over 3 x 10(-9) M, alpha-zearalanol (livestock anabolic) over 3 x 10(-7) and bisphenol-A (plastic) over 3 x 10(-6) M. Small amounts of estrogen receptor were present in the TECs. The above results clearly indicate that natural and environmental estrogens directly modulate TECs to produce thymic hormone probably through an estrogen receptor mechanism. Furthermore, our finding may be useful for evaluating biological effects of chemicals with estrogenic activity.

Percutaneous Nucleotomy in Elite Athletes

Percutaneous nucleotomy in elite athletes is considered a minimally invasive treatment of lumbar disc herniation. However, long-term effectiveness has not been established by careful follow-up studies. This article evaluates the outcome of percutaneous nucleotomy in elite athletes who have undergone the procedure. Thirty elite athletes with lumbar disc herniation who underwent percutaneous nucleotomy and had been followed for at least 2 years were compared with a matched group of 42 nonathletes. The outcome in athletes was worse than in nonathletes. Early return to vigorous sports activity in less than 3 months correlated with increased symptoms. Similarly, more extensive resection of disc material was associated with an unexpected rapid worsening of the outcome and the lower rate of return to preoperative sports. Patient selection and postoperative management of athletes and nonathletes undergoing percutaneous nucleotomy should be the same, and the procedure in athletes is probably not worthwhile if they do not obey postoperative management such as the timing of return to sports activity.

Sex hormones affect the intracellular activation signal in mitogen-stimulated human blood lymphocytes

Abstract The present study was an attempt to elucidate the effect of sex steroids (estradiol-17 β and 5 α -dihydrotestosterone) on the mitogen-stimulated human peripheral blood lymphocytes (PBL) proliferation. Our findings were as follows: (a) the proliferation of PBL in response to phytohemagglutinin (PHA) was mediated by protein kinase C (PKC) activity, but a strong inhibitory effect of sex steroids on the PKC activity of PHA-stimulated PBL was observed; (b) cytoplasmic extracts of PHA-stimulated PBL showed high activity as an activator of DNA replication (ADR) as well as increased levels of the mitosis stimulator p34cdc2 kinase, and the steroid hormones studied all significantly reduced these activities; and (c) these effects of sex steroids are similar to those found with hydrocortisone in parallel experiments. The results suggest that the cytoplasmic signal-generating system stimulating DNA synthesis and mitosis is inhibited in PHA-stimulated PBLs by several steroid hormones. The inhibition affects different factors stimulating DNA replication and cell proliferation.

Estrogenic xenobiotics affect the intracellular activation signal in mitogen-induced human peripheral blood lymphocytes : immunotoxicological impact

The present study was an attempt to elucidate the effect of estrogenic xenobiotics on the proliferation of mitogen-stimulated human peripheral blood lymphocyte (PBL). Our findings follow: (a) the proliferation of PBL in response to phytohemagglutinin (PHA) was mediated by protein kinase C activity, but estrogenic xenobiotics had a strong inhibitory effect on protein kinase C activity of PHA-stimulated PBL; (b) cytoplasmic extracts from PHA-stimulated PBL greatly activated DNA replication, but estrogenic xenobiotics had a strong inhibitory effect on these activities. The results suggest that the cytoplasmic signal-generating system in mitogen-treated PBL is inhibited by estrogenic xenobiotics, and that the defect occurs at all stages in the sequence of events leading to DNA synthesis and cell proliferation.

Natural and environmental oestrogens increase expression of SS-A/Ro autoantigen in the salivary gland of ovariectomized immature rats

Abstract SS-A/Ro autoantibodies are detected at high levels in patients with autoimmune diseases such as Sjogren’s syndrome. It has been reported that natural oestrogen is capable of inducing cell surface expression of SS-A/Ro autoantigens in salivary glands. We analyzed the effect of environmental oestrogens (i.e. oestrogenic xenobiotics) on the expression of the 52 kDa SS-A/Ro autoantigen in the rat salivary gland by reverse transcriptase polymerase chain reaction (RT-PCR) and in situ hybridization (ISH). Plant- or plastic-derived environmental oestrogens induced up to approximately 3.5-fold increase in 52 kDa SS-A/Ro mRNA levels in rat salivary gland compared to levels in untreated animals. The ISH results paralleled the RT-PCR results. These findings suggest that environmental oestrogen stimulation can induce the expression of autoantigens such as SS-A/Ro.