Patent Application
20060206172
Decreased neuronal energy production and increased oxidative stress are believed to be major components in the onset of Parkinson's Disease. It is believed that the substantia nigra contains high levels of iron, which helps catalyze oxygen to reactive oxygen species (ROS). The ROS then degrade dopamine-containing neurons. It is further believed that neurotoxins may be the cause of decreased neuronal energy output in the substantia nigra.
The literature describes the general use of anti-oxidants as potent neuroprotective agents for Parkinson's disease. For example, Dugan, Parkin. Relat. Disord., 1002, Jul. 7, (3) 243-6, describes the use of fullerene-based antioxidants as neuroprotective drugs. In addition, oral administration of ascorbic acid has been tried as a therapy for Parkinson's Disease. To date, however, none of the therapies involving systemic administration of anti-oxidants has been shown to be successful. One possible reason for their failure was their inability to cross the blood brain barrier.
This invention relates to an implantable diode that emits red light onto the substantia nigra as a treatment for Parkinson's Disease (PD).
It has been reported in the literature that near infra-red light saves neurons that have been challenged by neurotoxics from apoptosis. In particular, Wong-Riley, J. Biol. Chem. 2004, e-pub Nov. 22, reports that irradiating neurons with 670 nm red light significantly reduced neuronal cell death induced by 300 mM KCN from 83.6% to 43.5%.
The general concept of repairing brain cells through red light irradiation is also well supported by the literature. Wollman, Neurol. Res. 1998, Jul. 20(5) 470-2 reports that providing daily 3.6 J/cm2 doses of red light from a He—Ne laser to cortex explants resulting in caused a significant amount of sprouting of cellular processes outgrowth. Wollman concludes that the irradiation induces neurite processes sprouting and improves nerve tissue recovery. Similarly, Wollman, Neurol. Res. 1996 Oct. 18(5) 467-70 reports the enhanced migration and massive neurite sprouting of cultured rat embryonal brain cells subject to an 8 minute dose of a 0.3 mW, He—Ne laser. Therefore, the red light of the present invention may further cause repair and regeneration of damaged dopaminergic cells.
Therefore, in accordance with the present invention, there is provided a method of treating a patient having Parkinson's Disease, comprising the steps of:
Also in accordance with the present invention, there is provided a method of treating a patient having Parkinson's disease, comprising the steps of:
Also in accordance with the present invention, there is provided a device for treating a patient having Parkinson's disease, comprising:
Without wishing to be tied to a theory, it is believed that the therapeutic neuroprotective and neuroregenerative effects of red light described above may be due to
It is believed that irradiating neurons in the brain with red light will likely increase ATP production from those neurons. Mochizuki-Oda, Neurosci. Lett. 323 (2002) 208-210, examined the effect of red light on energy metabolism of the rat brain and found that irradiating neurons with 4.8 W/cm2 of 830 nm red light increased ATP production in those neurons by about 19%.
Without wishing to be tied to a theory, it is further believed that the irradiation-induced increase in ATP production in neuronal cell may be due to an upregulation of cytochrome oxidase activity in those cells. Cytochrome oxidase (also known as complex IV) is a major photoacceptor in the human brain. According to Wong-Riley, Neuroreport, 12:3033-3037, 2001, in vivo, light close to and in the near-infrared range is primarily absorbed by only two compounds in the mammalian brain, cytochrome oxidase and hemoglobin. Cytochrome oxidase is an important energy-generating enzyme critical for the proper functioning of neurons. The level of energy metabolism in neurons is closely coupled to their functional ability, and cytochrome oxidase has proven to be a sensitive and reliable marker of neuronal activity. Nonetheless, there is some doubt of an association between defects in cytochrome c oxidase in the substantia nigra and Parkinson's Disease. Itoh, Mov. Disord. 1997, Jan. 12(1) 9-16.
By increasing the energetic activity of cytochrome oxidase, the energy level associated with neuronal metabolism may be beneficially increased. Indeed, the literature reports that red light reverses the inhibitory effects of neurotoxins upon cytochroame oxidase activity, leading to increased energy metabolism in neurons functionally inactivated by toxins. Wong-Riley Neuroreport 12(14) 2001:3033-3037 and Wong-Riley, J. Biol. Chem., e-pub, Nov. 22, 2004.
According to Kamanli, Cell Biochem. Func. 2004, 22:53-57, catalase detoxifies hydrogen peroxide and converts lipid hydroperoxides into non-toxic alcohols, and is essential for the inhibition of inflammation related to the function of neutrophils.
Gonzalez, Cell Biology Int'l, 28(2004) 373-80, reports the effectiveness of catalase in enhancing the viability of PD cells in culture. In particular, Gonzalez reports that 50 U/ml catalase increased the in vitro viability of cerebellar granule cells exposed to MPP+neurotoxin from about 50% to about 75%. Furthermore, it is believed that catalase is superior to the anti-oxidants recited in the prior art because it is not only an anti-oxidant, it is also neurotrophic towards CNS neurons. See Wallicke, J. Neuroscience, April 1986, 6(4), 1114-21.
Romm, Biull. Eksp. Biol. Med. 1986 October 102(10) 426-8 reports that laser irradiation of wounds results in a decreased chemiluminescence that is attributable to activation of catalase in the tissue fluid.
Therefore, it is believed that irradiating the substantia nigra with an effective amount of red light will therapeutically increase of the activity of catalase in the irradiated region, thereby attenuating the deleterious effect of hydrogen peroxide upon the dopamine neurons in the substantia nigra.
According to Kamanli, supra, SOD catalyses dismutation of the superoxide anion into hydrogen peroxide.
SOD has been shown to be neuroprotective in a rat model of Parkinson's disease. Nakao Nat. Med. 1995, Mar. 1, (3) 226-231, reports that the survival of grafted dopaminergic neurons in transgenic rats designed to overexpress Cu/Zn SOD was about four times higher than those in control rats, and there was also a similar increase in functional recovery.
Vitreshchak, Bull. Exp. Biol. Med. 135(5) May 2003 430-432, reports that He—Ne irradiation of blood from Parkinson's patients produced a normalization of their Cu—Zn SOD activity. This means that patients having lower than normal levels of SOD increased their SOD to near normal levels. This paper further reports a decrease in the severity of PD (from 72 to 58 points) in these patients.
The literature repeatedly reports that red light irradiation of inactivated SOD increases its activity. For example, Vladimirov, Biochemistry (Moscow) 69(1) 2004, 81-90 provides a review including the photoreactivation of Cu—Zn SOD under He—Ne laser. Karu, Laser Ther. 1993, 5, 103-9 reports that reactive oxygen species in human blood were found to be suppressed after laser diode illumination at 660 nm, 820 nm, 880 nm and 950 nm. This affect has been attributed by other authors to the activation of SOD or catalase. Volotovskaia Vopr Kurortol Zizioter Lech Fiz Kult 2003 May-June(3)22-5 reports that 632 nm He—Ne laser irradiation of blood has an anti-oxidant effect as shown by activation of SOD. Ostrakhovich Vestn Ross Akad Med Nauk. 2001(5) 23-7 reports that infrared pulse laser therapy of RA patients caused an increase in SOD activity. Gorbatenkova Biofizika, 1988 July-Aug. 33(4) 717-9 reports that SOD that was inactivated by hydrogen peroxide was reactivated by a 450-680 nm red light laser. Vladimirov, Free Rad. Biol. Med. 1988, 5(5-6) 281-6 reports the inactivation of SOD by its incubation in a low pH 5.9 solution and its subsequent reactivation by helium-neon laser light. Catalase was found to be reactivated as well. Cho, In Vivo, 2004, Sept.-Oct. 18(5) 585-91 reports on the use of low level laser therapy (LLLT) to treat knee joints that have been induced with OA by injection of hydrogen peroxide. SOD was reported to increase about 40% in the OA group as compared to controls.
Therefore, it is believed that irradiating the substantia nigra with an effective amount of red light will therapeutically increase of the activity of SOD in the irradiated region, thereby attenuating the deleterious effect of superoxide anion upon the dopamine neurons in the substantia nigra.
Since infrared light is known to induce molecular vibrations (the basis of infrared spectroscopy), one could easily theorize that the use of IR light, particularly higher energy IR (e.g. shorter wavelengths 600-900 nm) could induce vibrations in the enzymes (proteins) of interest (such as catalase or SOD). It may be that the activity of these enzymes is inhibited or inactivated by weak intermolecular attractions, such as hydrogen bonding, Van der Waals, or ion chelation, causing sub-optimal protein conformations, and that the introduction of red light energy causes molecular vibrations sufficient to disrupt these weak forces, thereby allowing the enzyme to return to it's active 3-D conformation upon relaxation. If such a mechanism of action was accurate, the adjunctive use of solutions to create slight changes in the local environment (pH, ionic strength, solvation) during the treatment could have profound effects upon the treatment, e.g. synergistic.
According to Leung, Laser Surg. Med. 31:283-288 (2002), nitric oxide enhances oxidative insult by reacting with superoxide anion to form a stronger oxidant, peroxynitrite, which leads to mitochondrial dysfunction, DNA damage and apoptosis. As a result, excess NO has been implicated as a contributing factor to dopaminergic cell loss causing Parkinson's disease. Ebadi, Antioxidants & Redox Signaling, 5(3), 2003, pp. 319-335.
Leung, supra, investigated the effect of low energy red laser after stroke in rats, and found that red light can both suppress NO synthase activity (and upregulate the expression of TGF-β1). In particular, Leung found that irradiating a portion of the rat's brain with a 660 nm red light (average power 8.8 mW, 2.64 J/cm2) reduced NOS activity up to about 80% over that in unirradiated stroke rats, and up to about 60% over the NOS activity in normal rats. Leung concluded that the main findings of the study was that low energy laser may be protective by suppressing the activity of NOS and upregulating the expression of TGF-β1 in cerebral ischemia and reperfusion.
Without wishing to be theory, it is believed that irradiation of the substantia nigra portion of a Parkinson's brain will similarly therapeutically suppress NO synthase activity, thereby attenuating peroxynitrite activity.
Preferably, the red light of the present invention has a wavelength of between about 650 nm and about 1000 nm. In some embodiments, the wavelength of light is between 800 and 900 nm, more preferably between 825 nm and 835 nm. In this range, red light has not only a large penetration depth (thereby facilitating its transfer to the fiber optic and SN), but Wong-Riley reports that cytochrome oxidase activity is significantly increased at 830 nm, and Mochizuki-Oda reported increased ATP production via a 830 nm laser.
In some embodiments, the wavelength of light is between 600 and 700 nm. In this range, Wong-Riley reports that cytochrome oxidase activity was significantly increased at 670 nm. Wollman reports neuroregenerative effects with a 632 nm He—Ne laser.
In some embodiments, the light source is situated to irradiate adjacent tissue with between about 0.02 J/cm2 and 200 J/cm2 energy. Without wishing to be tied to a theory, it is believed that light transmission in this energy range will be sufficient to increase the activity of the cytochrome oxidase and anti-oxidant activity around and in the substantia nigra. In some embodiments, the light source is situated to irradiate adjacent tissue with between about 0.2 J/cm2 and 50 J/cm2 energy, more preferably between about 1 J/cm2 and 10 J/cm2 energy.
In some embodiments, the light source is situated to produce an energy intensity of between 0.1 watts/cm2 and 10 watts/cm2. In some embodiments, the light source is situated to produce about 1 milliwatt/cm2.
Of note, it has been reported that the neuroprotective effects of red light can be effected by a single irradiation on the order of minutes. Wong-Riley, J. Biol. Chem. 2004, e-pub Nov. 22, reports that irradiating neurons with 670 nm red light for only ten minutes results in neuroprotection. Similarly, Wong-Riley Neuroreport 12(14) 2001:3033-3037 reports that a mere 80 second dose of red light irradiation of neuron provided sustained levels of cytochrome oxidase activity in those neurons over a 24 hour period. Wong-Riley hypothesizes that this phenomenon occurs because “a cascade of events must have been initiated by the high initial absorption of light by the enzyme”.
Therefore, in some embodiments of the present invention, the therapeutic dose of red light is provided on approximately a daily basis, preferably no more than 3 times a day, more preferably no more than twice a day, more preferably once a day.
In some embodiments, the red light irradiation is delivered in a continuous manner. In others, the red light irradiation is pulsed in order to reduce the heat associated with the irradiation. Without wishing to be tied to a theory, it is believed that pulsed light may be more effective in achieving the vibratory oscillation of the catalase and SOD molecules.
In some embodiments, red light is combined with polychrome visible or white light Thus, there may be a substantial benefit to providing a local radiation of the substantia nigra with red laser light. The red light can be administered in a number of ways:
1) By implanting near the skull an implant having a red light LED, an antenna and a thin fiber optic terminating at the substantia nigra, and telemetrically powering the LED via an external antenna to deliver red light through the fiber optic to the substantia nigra.
2) By placing a fiber optic having a proximal light collector at the interior rim of the skull and running it to the substantia nigra, and then irradiating the proximal end via an external red light source. Red light can penetrate tissue up to about one cm, so it might be able to cross the skull and be collected by the collector.
3) By implanting a red light LED in the skull, and powering the LED via an internal battery.
In each case, there is produced an effective amount of local red or infrared irradiation around the substantia nigra. This light would then increase local ATP production, and enhance SOD and catalase activity, thereby increasing the metabolism in and reducing the oxidative stress upon the substantia nigra.
Now referring to
a) a Red Light emitting diode (LED) 11, and
b) an antenna 21 in electrical connection with the LED.
In use, the surgeon implants the device into the brain of the patient so that the device is adjacent to a portion of the substantia nigra. The Red light produced by the implant will then irradiate that portion of the substantia nigra.
In order to protect the active elements of the device from cerebrospinal fluid (“CSF”), in some embodiments, and again referring to
In some embodiments, it may be desirable to locate the light emitting portion of the implant at a location separate from the LED, and provide a light communication means between the two sites. The light communication means may include any of a fiber optic cable, a wave guide, a hollow tube, a liquid filled tube, and a light pipe.
Now referring to
Such a configuration would allow the distal end of the fiber optic to be located deep within the patient's brain near the substantia nigra and yet have the light source and associated components located near or in the skull in a less sensitive region. This configuration allows easier access to the light/controller should the need arise for service or maintenance, and also allow for more efficient transdermal energy transmission. Moreover, by using a hollow tube with reflective internal surfaces, light and therapeutic fluids (such as a fibroblast graft) could be delivered to the implanted device. The light source/controller implanted near the patient's skull could also be a simple, hollow chamber made to facilitate the percutaneous access described above. The advantages and benefits of this system include:
In use, the surgeon implants the device into the brain of the patient so that the antenna is adjacent the cranium bone and the distal end of the fiber optic cable is adjacent to the substantia nigral region of the brain.
In some embodiments, the proximal end portion of the fiber optic cable is provided with a cladding layer 41 of reflective material to insure that Red light does not escape the cable into untargeted regions of brain tissue.
In some embodiments, the distal end portion of the fiber optic cable includes a plurality of fiber optic tynes 51 extending from the cable (as shown in
In some embodiments, the tynes located at distal end portion of the fiber optic cable are placed around the substantia nigra.
Because long wavelength red light can penetrate up to many centimeters, it might be advantageous to transcutaneously deliver the light the fiber optic. Now referring to
In some embodiments, as in
To enhance the propagation of light emitted from the end of the fiber, a lens could be placed at the distal end of the fiber to spread the light, or a diffuser such as a small sheet or plate of optical material could be used to create more surface area. Alternatively, one could create a series of lateral diffusers, such as grooves or ridges, along the distal portion of end of the fiber to spread light out from 360 degrees perpendicular to the axis of the fiber, as well as emanating directly out from the end of the fiber.
Now referring to
Now referring to
In some embodiments, and now referring to
When the implant is coupled with external energy, power can be transmitted into the internal device to re-charge the battery.
In some embodiments, the light generated by the implant is powered by wireless telemetry integrated onto or into the implant itself. In the
In one embodiment, the implant may have an internal processor adapted to intermittently activate the LED.
In some embodiments, the telemetry portion of the device is provided by conventional, commercially-available components. For example, the externally-based power control device can be any conventional transmitter, preferably capable of transmitting at least about 40 milliwatts of energy to the internally-based antenna. Examples of such commercially available transmitters include those available from Microstrain, Inc. Burlington, Vt. Likewise, the internally-based power antenna can be any conventional antenna capable of producing at least about 40 milliwatts of energy in response to coupling with the externally-generated Rf signal. Examples of such commercially available antennae include those used in the Microstrain Strainlink™ device. Conventional transmitter-receiver telemetry is capable of transmitting up to about 500 milliwatts of energy to the internally-based antenna.
In some embodiments, and now referring to
In some embodiments, the light source is provided on the implant and is adapted to be permanently implanted into the patient. The advantage of the internal light source is that there is no need for further transcutaneous invasion of the patient. Rather, the internally-disposed light source is activated by either a battery disposed on the implant, or by telemetry, or both. In some embodiments of the present invention using an internal light source, the light source is provided by a bioMEMs component.
Because use of the present invention may require its repeated activation by Rf energy, it would be helpful if the user could be guaranteed that the implant remained in the same place within the skull. Accordingly, in some embodiments, and now referring to
It is anticipated that the present invention would be useful in treating neurodegenerative diseases such as Parkinson's Disease, SRO Syndrome, progressive Supemuclear Palsy, parkinsonism and Alzheimer's Disease.
It is anticipated that functional benefits following red light irradiation are site-specific. In some embodiments, the fiber optic is placed to irradiate the dorsal striatum; the lateral striatum; the caudate nucleus; the putamen; the posterior putamen; the anterior putamen/caudate nucleus complex.
In some embodiments, the fiber optic is placed to irradiate the substantia nigra. Therefore, the fiber optic may be placed within about an 4 mm of the substantia nigra. The surgeon may access the substantia nigra though the brain parenchyma using stereotactic MRI guidance. As it is desirable to use a flexible material as the fiber optic in order to reduce migration, the distal end of the fiber optic may be placed near the substantia nigra with the help of a relatively stiff introducer cannula.
In some embodiments, the patient can receive a unilateral fiber optic, while in other the patient can receive bilateral fiber optic. In some embodiments, a plurality of cables is used to deliver light to each target region.
In some embodiments, a red light source or red light collector and the proximal end of the fiber optic are placed in the chest. This allows the surgeon to conduct maintenance activity on an implanted light source without having to re-open the cranium. In addition, location within the chest also lessens the chances of surface erosion.
In some embodiments, electrical stimulation of a portion of the brain (other than the substantia nigra) is carried out. In some embodiments, the stimulation is accomplished with a separate conductive wire. In others, the stimulation is in part accomplished by painting a conductive strip upon a longitudinal surface of the fiber optic cable.
