LECTURER  (IAEA EXPERT MISSION)

Introduction:

Under the Advance Training Course cum Master Degree program, Dr. William Tomford visited the Bangkok Biomaterial Center to deliver lectures on advanced topics in tissue banking. During his expert mission, he delivered lectures on history of tissue banking in USA, tissue recovery and donor selection criteria, radiation sterilization, disease transmission through bone grafting, processing, bone histology and remodelling,

Lecture Topic: HISTORY OF TISSUE BANKING

The first successful bone allograft in human was done by Scottish surgeon Macewan (1880). The modern practice of bone grafting was invented by Macewen in the Infirmary of Glasgow in 1880. He transplanted fresh allogeneic bone to replace a 11 cm defect of the humeral shaft lost through osteomyelitis.

Tissue preservation was started by Alexis Carrel (1910). The first USA Tissue Bank was started in 1942 in North USA by Inclan, Havana, Cuba. Then Dr. Wilson started a femoral head bank. Hayatt (1950) developed the technique of freeze drying for tissue preservation.

Currently about 200000 allografts are used in USA per year. This is instead of other bone substitutes which are used over 100000 per year.

By 1977 there were 20 tissue banks in USA mostly in hospitals. By 1983-84 no of tissue banks were increased upto about 120. But with the beginning of AIDS crisis in 1981, the situation was unfavourable for us tissue banks. In 1984-85 AIDS transmission through allografts created many problems. Then no of tissue banks were reduced to 30 by 1990. At present only 10 tissue banks are in operation in USA.

Discussion on activities of BBC to find donors:

BBC is mainly looking for donors from Forensic department of Siriraj Hospital and Police Forensic Institute. This includes the donors from traffic accidents, homicides, suicides etc. Brain dead donors are received with the coordination of organ transplant unit of Thai Red Cross.

According to the recent survey, on public attitudes on tissue donation, about 29% are willing to donate tissues. Interviewing next of kin frequently to find potential donors, is very important aspect.

Expert suggested to visit wards, ICU, emergency units everyday and discuss with doctors and nurses there to get their help to find donors. Educate them with tissue bank donor selection criteria will help to find the potential donors. In USA the organ donation level is static from 1995 to 1999 but tissue donation is increasing every year. Organ donation level is approximately 1500 per year while tissue donation in 1999, 5000 per year. And also he proposed the activities such as donor awareness week every year involving president of the country, driving license check off system, more coordination with doctors in hospitals and forensic institutes etc.

	Coordination with hospitals
	Coordination with Police Forensic institute.
	TV programmes
	General public talks.
	Scientific talks to professionals such as doctors, residents etc.
	Radio programmes.
	General magazines.
	Scientific magazines.
	News papers
	Exhibitions
	Public seminars for users and producers.
	Tissue Donation Society Foundation.
	Tissue Donation Recruitment Programme.
	Ambassador of tissue donation.

Introduction to tissue recovery:

Maintaining the aseptic technique is very important during tissue recovery. Tissue recovery should be done in a professional, dignified manner, showing utmost respect and concern for the deceased and the bereaved relatives. First to recover fascia lata and then tibia with patella tendon, femur, fibula subsequently. Femur condyle and proximal femur also can be recovered with ligament capsule. Classical joints such as knee, hip, shoulder also can be recovered.

Reconstruction is the most important part after tissue recovery. All efforts should be directed to restore the body to its natural state. A plastic bone or a wooden stick approximating the size of donor bone is used to replace the harvested bone.

The Director of BBC Prof Vajaradul showed the results of an allograft use after 11 years. The patient visited BBC and showed her improvement on walking. Expert proposed to do a bone scan to further investigate the healing of allograft.

Then the Director explained some new innovations of BBC such as loose bone fragment retransplantation, cranium retransplantation, bone tablets, hydroxy apatite ocular implant etc.

Lecture Topic: DONOR SELECTION:

Donor evaluation is done using history, physical examination and blood tests.

History: History of hepatitis, blood transfusion, infectious diseases, sexual behaviors etc.

Physical Examination: Tattoos, needle marks, infected wounds etc.

Blood tests: Anti HIV 1/2 by PCR or p24 Ag

HBsAg or Anti HBcAg

VDRL

Hepatitis A:

Unlikely to be transmitted.

Infection self limited.

No chronic carrier state.

Transient Viremia - low titer.

Anti Hepatitis A virus antibody is common.

Hepatitis B:

The most important type for tissue banking.

Donor history is very important to avoid window period.

Blood screening tests such as HBsAg, Anti HBc are used to detect.

Disease Transmission:

The first case of HIV transmission through allograft was reported in 1985 in USA.

Case1: (1984)

Donor is from a denied disease. Not tested for AIDS.

Graft used: Deep frozen femoral head.

Recipient: Spinal fusion for scoliosis.

Developed Pneumatocytis carinti Pneumonia

Patient died after 4 years of transplantation due to AIDS. This shows that freezing cannot kill HIV virus.

The expert repeatedly paid attention on donor evaluation criteria such as medical history, physical examination and blood tests.

Case 2: (1985)

Donor: Brain dead donor died on Gun Shot Wound on head. No known disease was with this donor. No high risk factors for HIV. HIV tests from two laboratories showed negative.

Grafts: Organs and tissues were stored, freeze dried or deep frozen or washed.

Recipients:

All the organ recipients died of AIDS within 1 year.

Then all the tissue grafts recipients were tested for HIV 1 in 1989.

Tissues which transmitted HIV virus:

Frozen femoral heads (2)

Frozen patella tendon (1)

Tissues which did not transmit HIV virus:

Frozen femoral heads(reamed/cemented) (1)

Freeze dried bone chips (washed/ETOH treated) (38)

Freeze dried patella tendon-tubercle (1)

This shows that processed grafts that have undergone through a cleaning process to remove blood cells cannot transmit HIV. But frozen femoral head also did not transmit HIV. This is due to temperature increased of bone cement was enough to kill HIV.

Conclusion:

Risk of transmission = amount of blood

Discussion with Forensic doctors

Discussion:

Prof. Vajaradul started the discussion by presenting a recent survey done at Siriraj Hospital on attitudes of public on tissue donation. Only about 30% agreed for donation. Under such circumstances, BBC needs more help from all forensic doctors and pathologists in the country.

The expert joining the discussion, expressed that attention must be paid to have more deceased donors. Frequent visits to emergency room, ICU, wards are required to convince doctors and nurses to find potential donors. We have to educate forensic doctors and pathologists about tissue bank donor selection criteria. If there is a potential donor, they can call tissue bank. Then tissue bank will be able to contact the families for further action. The recovery team with required equipment go to morgue and do recovery there.

In Boston, the most requent recipients are cancer, trauma and sport injuries. They were having two donors a week from morgue as they are coordinating with pathologists and forensic doctors. Their pathologists select the potenial donors according to the donor selection criteria list given by the tissue bank.

The Research and International Coordinator Mr. Reyaz Alam Qayami presented some of the new innovations of BBC such as loose bone fragment retransplantation, cranium retransplantation, bone tablets, pinna reconstruction using rib cartilage, ambassador of tissue donation etc.

Lecture topic: RADIATION STERILIZATION

Comparison between ETO and irradiation

D₁₀ value: The dose required to reduce a microbial population by 1 log cycle.

The D10 for HIV virus = 4kGy -6kGy

Therefore radiation cannot be used to inactivate HIV virus as high doses required.

- Comparative concentration (sera/blood)

HBV 10⁹ - 10¹⁰/cc

HIV 1 - 10³/cc

- Safety dose to inactivate HIV (D₁₀ = 0.4 mrad)

At lowest titer

0.56 X (6+1) = 3.92 mrad

At highest titer

0.99 X (6+3) = 9 mrad

- Radiation and tissue damage:

2 mrad: protein degredation

3 mrad: biomechanical effect - intramolecular bonds breakage

Radiation and microorganisms:

<2 M rad: Bacterial sterilization, may not kill virus,

>2 M rad: may kill virus, destroy protiens

>4 M rad: Kill most viruses, weaken the tissue.

As radiation cannot be used to kill virus, processing steps such as pasteurization, washing, chemical treatment etc have to be used.

In USA, they uses several washing steps to remove blood cells from cancellous bones and treat with chemicals such as H₂O₂, NaOCl, C₂H₅OH etc.

Cortical bones are washed by a high pressure water jet to remove periostium.

Wolff's Law: Bone remodelling occurs according to the stress.

When a massive allograft is transplanted, remodelling occurs very slowly. Even after 3-5 years, new bone formation can be seen only at osteosynthesis sites. This is because massive allograft is an avascular tissue. Therefore it cannot remodel. The fatigue fracture will be the results.

Repair confirmed to superficial surface slow or negligible internal remodelling.

Immune response

priosteum residuals of the graft

haemorrhaging canals contain endothelial cells of blood vessels which cause immune response.

Visit to Priest's Hospital:

Discussion with Dr. Chalao on Hydroxy apatite ocular implant(HAOI)

HAOI are successfully being used in this hospital to treat blind eye to repair the eye socket for prosthesis. Advantage over the glass eye ball is no protrusion occur from HAOI. And also it gives movements for artificial eye so that the blind eye cannot be recognized. Dr. Chalao showed a successful patient whose eye was treated with HAOI. The patient can move artificial eye with other eye.

HAOI is not absorbed because it is not used for the weight bearing purpose. A small hole is prepared on HAOI to fix the peg which is used to fixed the artificial eye.

Complications:

Pore size is too large. Therefore capillary attraction will be late as less help to blood vessels to grow inside the graft.

When ointment is applied, ointment goes inside pores and block neovasculerization.

Tissues covered the HAOI melts and exposed the graft before drilling a hole. The Fascia lata autografts hacve to be used to cover the surface.

If the hole is eroded after some times, a larger peg has to be used.

- Surgeon's Responsibility:

	Inform the patient of risks and benefits
	Keep records of grafts and recipients for 10 years
	Inform any adverse reaction to the tissue bank
	If decease transmission, inform the relevant authority.

- Tissue Banks Responsibility:

	Provide safe tissue grafts
	Inform the surgeon about the risks.
	Keep accurate records on grafts preparation, characteristics, grafts recipients.
	Reporting and recording problems

- Terminology:

Isografts: A graft between genetically identical individuals.

Autografts: Graft from one site to another site of same individual.

Allografts: Grafts from one individual to another individual of the same species.

Xenografts: Grafts between individuals of different species.

Osteogenesis: New bone formation from transplanted autografts. Ex: illiac crest bones

Osteinduction: Underdeveloped tissue transformed to bone by one or more inducing agents such as BMP. Ex: DBM, AAA bone

Osteoconduction: Scaffolding which permits bony ingrowth. Ex: Freeze dried and deep frozen bone grafts.

- Cortical Bone:

Slow replacement.

Periosteal endosteal.

Cancellous Bone:

Gradual replacement

Revasculerization

Osteoclasts: remove the bone cells.

Osteoblasts: deposit new bone.

When cancellous bones are grafted, the blood vessels grow into the grafts and then bone forming cells such as osteoblasts and osteoclasts from host come into the site. Gradually old bone is replaced by new bone cells.

Rate of Revasculerization depend on:

Antigenicity

Union/stability

Disease/treatment (Adjuvant therapy, surgical protocol

Graft Incoorporation:

Determinant of rate and amount of new bone formation on, in, about a bone graft is the resence/Absence of living, histocompatible bone cells.

Host site environment

Biologic activity of the graft

Contact of graft with host bone

Stability of construction.

Stimulate osteoprogenitor cells to undergo differentiation to cartilage and bone through endochondral ossification (2, 7 are more active)

BMP - 2:

Native BMP, both shared good results.

Used for spinal fusion, osteonecrosis, fracture healing

BMP - 7:

Still Trial in human.

Involve tibial non-unions

Used BMP 7 with sponge.

PDGF: (Platelet Derived Growth Factors)

Stimulate soft tissue healing, not effective for long bones.

EGF: (Epidermal Growth Factors)

Not effective in bone healing.

TGF-b : (Transforming Growth Factor b

Stimulate chondrogenesis

Not as promising as BMPs.

FGF: (Fibroblast Growth Factors)

Used in treatment of myocardial infarction.

	Guardians of donors. Advocate for donors and donor families.
	Assurance safety. Continuous upgrade in testing/process.
	Preservation techniques. Development and application.
	Innovations. Types and uses.
	Advocacy. Non profit,
	Public awareness.

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