RADIOPARTICLES FOR RADIOPARTICLES FOR RADIOSINOVECTOMYRADIOSINOVECTOMY

María Graciela ArgüellesMaría Graciela Argüelles

Centro AtCentro Atóómicmicoo Ezeiza, Ezeiza,

ComisiComisióón Nan Naccional de Energional de Energíaía At Atóómicmicaa

Buenos Aires, República ArgentinaBuenos Aires, República Argentina

Rheumatoid arthritisRheumatoid arthritis

• It is an ubiquitous incapacitating disease that places It is an ubiquitous incapacitating disease that places substantial demands on health care resources. substantial demands on health care resources.

• It affects 1% to 2% of the population worldwide, with a It affects 1% to 2% of the population worldwide, with a woman -to- man prevalence ratio of 3:1. woman -to- man prevalence ratio of 3:1.

• The characteristic disease manifestations of RA are The characteristic disease manifestations of RA are joint pain, swelling and reduced mobility as a result of joint pain, swelling and reduced mobility as a result of the synovial tissue inflammation, the synovial tissue inflammation,

Rheumatoid arthritisRheumatoid arthritis

any synovial joint in the any synovial joint in the body can be affected by body can be affected by the disease. the disease.

Rheumatoid arthritisRheumatoid arthritis

Pannus can be considered the most Pannus can be considered the most destructive element affecting joints destructive element affecting joints in the patient with rheumatoid in the patient with rheumatoid arthritisarthritis.. It can attack articular It can attack articular cartilage and destroy it. cartilage and destroy it.

RadiosynovectomyRadiosynovectomy

• It consists of intra-articular injection of beta-emitting It consists of intra-articular injection of beta-emitting radionuclide in colloidal or particulate form, which comes into radionuclide in colloidal or particulate form, which comes into contact with synovium. Phagocytic cells absorb some of the contact with synovium. Phagocytic cells absorb some of the injected dose, which is transmitted to the synovium. injected dose, which is transmitted to the synovium.

• If the amount of radioactivity injected is If the amount of radioactivity injected is large enough the tissue will be destroyed. large enough the tissue will be destroyed. Regenerated tissue will be Regenerated tissue will be asymptomatic asymptomatic for 2-5 years. for 2-5 years.

• Compared with surgicalCompared with surgical synovectomy synovectomy, the radiation therapy , the radiation therapy is simpler and less traumatic, hospitalization time is shorter; is simpler and less traumatic, hospitalization time is shorter;

cost is lower and duration of relief is comparable. cost is lower and duration of relief is comparable.

Ideal radionuclideIdeal radionuclide

Pure beta-emitter or beta emitter with minimal gamma emissions.

5 mm < Tissue penetration < 10 mm

Short half-life

Low cost

Chemically pure

Non-toxic

RADIONUCLIDERADIONUCLIDE

Radionuclides Used for Radiation Radionuclides Used for Radiation SynovectomySynovectomy

RadionuclideRadionuclide Half Half life[days]life[days]

max. max. --energy energy [MeV][MeV]

tissue tissue penetration penetration depth [mm]depth [mm]

-energy [keV] -energy [keV]

Dy-165Dy-165 0,10,1 1,291,29 5,75,7 9595

Re-188Re-188 0,70,7 2,12 / 1,962,12 / 1,96 11,011,0 155155

Ho-166Ho-166 1,21,2 1,85 / 1,771,85 / 1,77 8,58,5 8181

Sm-153Sm-153 1,91,9 0,67 / 0,810,67 / 0,81 2,52,5 103103

Au-198Au-198 2,72,7 0,960,96 3,63,6 411411

Y-90Y-90 2,72,7 2,282,28 11,011,0 --

Re-186Re-186 3,73,7 1,071,07 / / 0,930,93 3,63,6 137137

Lu-177Lu-177 6,76,7 0,480,48 1,71,7 208208

Er-169Er-169 9,49,4 0,340,34 / / 0,350,35 1,01,0 --

P-32P-32 1414 1,711,71 7,97,9 --

Ideal particulate carrierIdeal particulate carrier

It must be taken up by synovial tissue.It must be taken up by synovial tissue.

It must form a stable complex with radionuclide.It must form a stable complex with radionuclide.

It must be It must be preparedprepared easily and reproducibly. easily and reproducibly.

Non-toxic.Non-toxic.

Non- allergenic.Non- allergenic.

PARTICULATE CARRIERPARTICULATE CARRIER

Finally, any biologically induced degradation of the agent Finally, any biologically induced degradation of the agent should ideally release the radionuclide in a chemical form should ideally release the radionuclide in a chemical form that rapidly egresses from the body.that rapidly egresses from the body.

Radionuclides productionRadionuclides production

ExperimentalExperimental

SAMARIUM-153 PRODUCTIONSAMARIUM-153 PRODUCTION

Target materialTarget material

Thermal neutron fluxThermal neutron flux

Irradiation timeIrradiation time

Specific activitySpecific activity

152152Sm (98.7 %) nitrateSm (98.7 %) nitrate

7.107.101313 n/cm n/cm22ss

36 hours36 hours

5-10 Gbq/mg5-10 Gbq/mg

HOLMIUM-166 PRODUCTIONHOLMIUM-166 PRODUCTION

Target materialTarget material

Thermal neutron fluxThermal neutron flux

Irradiation timeIrradiation time

Specific activitySpecific activity

165165Ho (100 %) nitrateHo (100 %) nitrate

1.101.101313 n/cm n/cm22ss

20 hours20 hours

4-5 Gbq/mg4-5 Gbq/mg

Nuclear purity controlNuclear purity control

Multichannel analyzer with HPGe detector.Multichannel analyzer with HPGe detector.

Gamma ray spectrum was identical to published nuclear Gamma ray spectrum was identical to published nuclear data.data.

Albumin microspheresAlbumin microspheres

• The microspheres were obtained by heat denaturalization The microspheres were obtained by heat denaturalization of a human serum albumin (HSA) emulsion in vegetable oil. of a human serum albumin (HSA) emulsion in vegetable oil.

A 10 % human albumin solution and olive oil were used. A 10 % human albumin solution and olive oil were used.

PARTICLES PREPARATIONPARTICLES PREPARATION

• The HSA solution was added, drop by drop, into the olive The HSA solution was added, drop by drop, into the olive oil stirring vigorously. oil stirring vigorously.

• The emulsion was heated up to 140 -160°C for one hour.The emulsion was heated up to 140 -160°C for one hour.

• The suspension was cooled and diluted The suspension was cooled and diluted with n-with n-hexane. hexane. It was filtrated with mesh It was filtrated with mesh 200 in order to discard the 200 in order to discard the particles over 75 µm. The supernatant was filtered thorough particles over 75 µm. The supernatant was filtered thorough membrane filter. membrane filter.

• The The microspheres were rinsed with acetone microspheres were rinsed with acetone and dried.and dried.

Particles size measurementParticles size measurement

It was performed using a optical microscope with It was performed using a optical microscope with micrometric ocular. micrometric ocular.

Size Distribution Of MicrospheresSize Distribution Of Microspheres

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

50%

.5-15 .15-25 25-35 35-45 45-55 60-80

µm

Electronic Electronic microscopymicroscopy photographies photographies

Hydroxyapatite particlesHydroxyapatite particles

Ca(NOCa(NO33))22 (NH(NH

44))22HPOHPO44

A voluminous precipitate was formed. It was A voluminous precipitate was formed. It was allowed to settle and the supernatant allowed to settle and the supernatant solution was discharged. solution was discharged.

pH pH 1212

Hydroxyapatite particlesHydroxyapatite particles

The precipitate was rinsed with hot water, dried at 150 °C and The precipitate was rinsed with hot water, dried at 150 °C and heated for an hour at 240 °C to remove the ammonium heated for an hour at 240 °C to remove the ammonium nitrate. By strong heating at 800 °C for an hour, the product nitrate. By strong heating at 800 °C for an hour, the product becomes largely anhydrous and hardened. The synthesis becomes largely anhydrous and hardened. The synthesis yield was always greater than 80%.yield was always greater than 80%.

Size Distribution Of HA MicroparticlesSize Distribution Of HA Microparticles

0%

5%

10%

15%

20%

25%

30%

35%

.5-15 .15-25 25-35 35-45 45-55 55-65

µm

Labelling with Labelling with 153153SmSm

Labelling was done in two steps:Labelling was done in two steps:

• 153153Sm-citrate was prepared by adding Sm-citrate was prepared by adding sufficient sufficient citric acid to the citric acid to the 153153SmClSmCl

33 solution to give a concentration solution to give a concentration

of 15 mg/ml citric acid in 0,1 N HCl. of 15 mg/ml citric acid in 0,1 N HCl.

• The radioactive solution was added to the particulate The radioactive solution was added to the particulate suspension (20 mg) stirring continuously (30 min, 37 °C). suspension (20 mg) stirring continuously (30 min, 37 °C).

• Radiolabelled particles were rinsed with saline and separated Radiolabelled particles were rinsed with saline and separated by centrifugation (5 min at 1000 rpm) and labelling efficiency by centrifugation (5 min at 1000 rpm) and labelling efficiency was determined. was determined.

• The microspheres were resuspended in 2 ml of saline. The microspheres were resuspended in 2 ml of saline.

Labelling efficiencyLabelling efficiency

The radioactive mixture was transferred to a centrifuge tube The radioactive mixture was transferred to a centrifuge tube using 4 ml of saline to rinse, centrifuged at 1000 rpm for 5 using 4 ml of saline to rinse, centrifuged at 1000 rpm for 5 minutes. The supernatant was then transferred to another minutes. The supernatant was then transferred to another tube. Measurements of radioactivity were made and tube. Measurements of radioactivity were made and labelling efficiency was calculated as percentage of initial labelling efficiency was calculated as percentage of initial activity.activity.

In vitro stabilityIn vitro stabilityStability of the labelled particles was studied in normal saline Stability of the labelled particles was studied in normal saline and 1% albumin solution, at 36°C over 48 hours. Albumin and 1% albumin solution, at 36°C over 48 hours. Albumin microspheres retained microspheres retained less than less than 80% of the initial activity after 80% of the initial activity after 48 h incubation48 h incubation..

HA particles retained radiactivity for 6 days.HA particles retained radiactivity for 6 days.

  3 days3 daysn = 6n = 6

6 days6 daysn = 6n = 6

Cumulative Cumulative Leakage *Leakage *

153153Sm-HASm-HA153153Sm-citrateSm-citrate

0.140.14++0.130.1337.237.2++1.21.2

0.320.32++0.200.2042.342.3++1.01.0

EXTRA-ARTICULAR LEAKAGE EXTRA-ARTICULAR LEAKAGE

* Blood, liver, kidneys, lungs, bone, urine.* Blood, liver, kidneys, lungs, bone, urine.

HoClHoCl33 Acetylacetone Acetylacetone

Complex Ho(AcAc)Complex Ho(AcAc)33

pH 7pH 7

Complex + PLAComplex + PLA MicrosparticlesMicrosparticles

Evaporation TechniqueEvaporation Technique

PLA particlesPLA particles

X-ray fluorescence and energy dispersive spectrometry X-ray fluorescence and energy dispersive spectrometry were used to determine the presence of Ho in the particles were used to determine the presence of Ho in the particles and complex stoichiometry. and complex stoichiometry.

The particle size distribution of The particle size distribution of microspheres was determined by microspheres was determined by electronic microscopy. electronic microscopy.

PLA particlesPLA particles

0%

10%

20%

30%

40%

50%

60%

0-10 .10-20 20-30 30-40 40-60 60-80

µm

Its diameter range was 20 µm.Its diameter range was 20 µm.

HOLMIUM-166 FERRIC HYDROXIDE HOLMIUM-166 FERRIC HYDROXIDE MACROAGGREGATES MACROAGGREGATES

166166HoClHoCl33 solution FeSO solution FeSO44solutionsolution

Coprecipitation Coprecipitation 166166Ho(OH)Ho(OH)33 / Fe(OH) / Fe(OH)33

Macroaggregates were washed twice with PVP solution.Macroaggregates were washed twice with PVP solution.

Particles were resuspended in saline and sterilized.Particles were resuspended in saline and sterilized.

Obtention Efficiency > 90 %.Obtention Efficiency > 90 %.

Quality controlQuality control

• Radiochemical purityRadiochemical purity: :

ITLC / SG – EDTAITLC / SG – EDTA

RRff Ho Ho3+3+ : 1.0 : 1.0

RRff particles : 0.0 particles : 0.0

• Size:Size:

light microscopylight microscopy

serial filtrationserial filtration

• In vitro stability:In vitro stability: SalineSaline EDTA solutionEDTA solution

• Pharmacological control :Pharmacological control : ToxicityToxicity SterilitySterility PyrogenicityPyrogenicity

- Normal New Zealand Rabbits- Normal New Zealand Rabbits

- Rabbits with antigen-induced - Rabbits with antigen-induced arthritisarthritis

• 0 weeks: intradermic injection 0 weeks: intradermic injection of ovoalbuminof ovoalbumin

• 3 weeks: intradermic injection 3 weeks: intradermic injection of ovoalbuminof ovoalbumin

Animal modelAnimal model

Animal modelAnimal model

• 6 weeks: intra-articular injection of ovoalbumin6 weeks: intra-articular injection of ovoalbumin

• 7 weeks : synovitis symptoms7 weeks : synovitis symptoms

• Intra-articular injection of Intra-articular injection of 166166Ho-FHMAHo-FHMA

• Gamma camera imagingGamma camera imaging

Gamma camera imagesGamma camera images

Zoom 1.0Zoom 1.0 Zoom 4.0 Zoom 4.0

4 h p.i.4 h p.i.

24 h p.i24 h p.i.

Marker Marker 99m99mTc Zoom 1.0 Body scanTc Zoom 1.0 Body scan

Gamma camera imagesGamma camera images