principles of organ transplant and renal transplant

PRINCIPLES INVOLVED IN ORGAN

TRANSPLANT

By - Dr NAVIL SHARMAGuide – Dr BALCHANDRA KASHYAPI

CONTENTS INTRODUCTION

Definition of terms Transplant immunology Graft rejection

PRINCIPLES Pre-operatives Intra-operatives Post-operative

COMPLICATIONS

RENAL TRANSPLATATION

ETHICAL CONSIDERATIONS

CONCLUSION

INTRODUCTIONDEFINITION OF TERMS

An organ transplant is a surgical procedure in which a failing organ is replaced by a functioning one from a donor with a compatible tissue type.Autograft - Transfer of organ from one part

to another in the same individual. E.g skin

graft, vuscular graft.

Allograft - from one individual to another

of the same species

Isograft - transfer of organ from one

individual to his or her monozygotic twins

Xenograft - transfer of organ from one

individual to another of different species

INTRODUCTIONDEFINITION OF TERMS

Orthotopic graft- graft placed in it normal anatomical position

Heterotopic graft - graft placed at a site different from the organ is normally

located

Organs that can be transplanted are:

Heart

Kidneys Liver Thymus

Pancreas Lungs Intestine

Tissues that can be transplanted are:

Bones Tendons Cornea

Vein Heart valves Skin of leg

TRANSPLANT IMMUNOLOGYThe immune system recognizes graft from someone else as foreign body and triggers

response via immune cells and substances they produce - cytokines and antibodies

(Responses are via; recognition, amplification and memory)

Immunity

IMMUNE CELLS

Lymphocytes : T-lymphocyte, B-lymphocyte, N-killer cells

Antigen presenting cells(APC) : macrophages, dendritic cells

The Effector Cells : Neutrophils , macrophages and T-lymphocytes

Humoral (Antibody mediated)

Cell mediated

LYMPHOCYTES T-LYMPHOCYTES

o Mediator of cell mediated immunity

o They recognizes MHC antigen on transplant tissues

o Cytotoxic T-cells produces cytotoxic factors (perforins, granzymes) implicated

in transplant rejection

B-LYMPHOCYTES

o Mediators of humoral immunity by antibody production.

o There activation is aided by cytokine and the T-helper cells

o Clonal selection generates plasma cells secreting antibodies.

o There are 5 major classes of antibodies or immunoglobulin; IgG, IgM, IgA, IgE and

IgD the 1st 3 are involve in graft rejection

N-KILLER CELLS

o Cells of innate immunity, capable of killing foreign targets without prior

sensitization

Cell-mediated immune response

Defend against intracellular pathogens/rejection

ActiveCytotoxic T cells

MemoryCytotoxic T cells

MemoryHelper T cells

Antigen-presenting cell

Antigen (2nd exposure)

Helper T cell

Engulfed by

Antigen (1st exposure)

Cytotoxic T cell

KeyStimulatesGives rise to

+

+

+

+

+ +

+

T-CELLS- Helper T cells- Cytotoxic T cells- Memory T cells

Cytotoxic T cell

PerforinGranzymes

TCRCD8

Class I MHCmolecule

Targetcell

Peptideantigen

Pore

Released cytotoxic T cell

Dying target cell

KeyStimulatesGives rise to

+

MemoryHelper T cells

Antigen-presenting cell

Helper T cell

Engulfed by

Antigen (1st exposure)

+

+

+

+ +

+

Defend against extracellular pathogens/Transplant rejection

MemoryB cells

Antigen (2nd exposure)Plasma cells

B cell

Secretedantibodies

Humoral (antibody-mediated) immune response

11

ANTIGEN PRESENTING CELLS(APC)o They capture antigens and display to lymphocytes e.g. Macrophages, dendritic cells

and follicular dendritic cells.

• Dendritic cells : initiate T-cells response

• Macrophages : Initiate effector phase of cell mediated immunity

• Follicular dendritic cells : display antigens to B-lymphocytes in humeral

response.

EFFECTOR CELLSo They eliminate antigens by phagocytosis

E.g neutrophils, macrophage and T-lymphocytes

TRANSPLANT ANTIGENS

Human leucocytes antigen (HLA) ;a group of highly polymorphic cell surface molecules

They act as antigen recognition unit on T-lymphocytes and are the major trigger for

graft rejection

Types : class1 – HLA- A,B,C present in all nucleated cells,

CD8+ recognizes class 1 HLA

class2 – HLA- DR, DP, DQ present only on APC

Class 2- HLA-DR are most important in rejection

CD4+ recognize class 2 HLA

Major histocompatibility complex MHC;o They are clusters of genes on the short arm of

chromosome 6 expressed on the cell surface as HLA i.e. genes that encode HLA.

ABOo These blood group antigen are expressed not only on

red blood cells but by most cell types as well.o Incompatibility leads to hyperacute rejection

Rejection of transplanted organs is a bigger challenge than the

technical expertise required to perform the surgery. It results mainly from HLA and ABO

incompatibility.Types of Graft Rejection

Hyperacute : o Immediate graft destruction due to ABO or preformed

anti- HLA antibodies.o Characterized by intravenous thrombosis and

interstitial hemorrhage.o Risk factors are previous failed transplant and blood

transfusionso Kidney transplant is vulnerable to hyperacute

rejection . Hyperacutly rejecting kidney rapidly becomes cyanotic, mottled, and flaccid and may excrete few drops of bloody urine.

o This form of rejection is rarely seen in today's practice

GRAFT REJECTION

Steps in the hyperacute rejection of a kidney graft.

Hyperacute Rejection

Acute :o Usually occurs during the first 6 months. o May be cell mediated (T-cell), antibody mediated or both.

o Characterized by cellular infiltration of the graft (cytotoxic, B- cells, NK cells

and macrophages).

o Histologically, humoral rejection is associated with vasculitis, whereas cellular

rejection is marked by an interstitial mononuclear cell infiltrate, edema, and

tissue injury as well as mild interstitial haemorrhage.

Chronic :o It occurs after 6 month .o Most common cause of graft failure. o Non- immunological factors contribute to the pathogenesis characterized by

myo-intimal proliferation in graft arteries leading to ischemia and fibrosis

PRINCIPLES

PRE-OPERATIVE

Patient selection and Evaluation

Counseling

Informed consent

Optimization

PATIENT SELECTION AND EVALUATION

1. RECIPIENT Patient who met the indication for transplant – ORGAN FAILURE

Clinical evaluation; history and physical examination to rule out other

diseases and co-morbidities

Immunological evaluation Blood group

Tissue typing & cross matching

Serology; HIV, Hepatitis, CMV, VDRL

Infection screening – septic work-up

Others ; CBC, clotting profile, FBS, ECG, LFT, RFT, tumour markers.

2. DONOR

I. Living donor : Donor remains alive and donates a renewable tissue/cell,

or donates an organ or part of an organ in which the remaining organ can

regenerate or take on the workload of the rest of the organ (single kidney donation,

partial donation of liver). A living donor should be healthy• Living unrelated donor (LURD)

• Living related donor. (LRD)

Advantages of living donor Improved graft survival

Less recipient morbidity

Early function and easier to manage

Avoidance long waiting time for transplant

Less aggressive immunosuppressive regimen

Contra-indications for living donoro Mental disease

o Disease organ

o Morbidity and mortality risk

o ABO incompatibility

o Crossmatching incompatibility

o Transmissible disease

Evaluation : to assess for suitability

o CLINCAL - history of risk factors for infection, malignancy in the past 5

years. Presence of co-morbidities

o ABO typing, Serology tests.

o Infection and malignant screening

o CT-Angiogram, Intravenous urography.

o HLA typing.

II. Deceased donor- Brain dead donors: Donors who have been declared brain-dead and whose

organs are kept viable by ventilators or other mechanical mechanisms until they can

be excised for transplantation.

o Normothermic patient.o No respiratory effort by the patient.o The heart is still beating.o No depressant drugs intake should be there while evaluating the

patient.o Individual should not have any sepsis, cancer (except brain tumour).o Not a HIV or hepatitis individual.

- Cardiac Death Donors (formerly non-heart beating donors) to increase the

potential pool of donors as demand for transplants continues to grow. These organs

have inferior outcomes to organs from a brain-dead donor.

FACTORS DETERMING ORGAN FUNCTION AFTER TRANSPLANT

DONOR CHARACTERISTICS■ Extremes of age

■ Presence of pre-existing disease in the transplanted organ

■ Haemodynamic and metabolic instability

PROCUREMENT-RELATED FACTORS■ Warm ischaemic time

■ Type of preservation solution

■ Cold ischaemic time

RECIPIENT-RELATED FACTORS■ Technical factors relating to implantation

■ Haemodynamic and metabolic stability

■ Immunological factors

■ Presence of drugs that impair transplant function

Tissue typing

The tissue typing laboratory carries out 3 tasks :

To determine the HLA type of blood for both donor and recipient by

PCR.

Lymphocyte cross-matching to exclude circulating antibodies in

recipient against HLA expressed by donor.

HLA antibody screening and specificity in recipient before and after

transplant to guide immunosuppressive therapy

Positive cross matching; o Recipient antibodies attacks donor’s.

o Not suitable for transplant

Negative cross matching; o Recipient antibodies donot attack donor

o Suitable for transplant

Methods;

o Micro-cytotoxic assay, mixed lymphocytes, flow cytometry,

DNA analysis.

Lymphocyte cross-matching

Typing procedures for HLA antigens. (a) HLA typing by microcytotoxicity.

(b) Because cells express numerous HLA antigens, they are tested separately with a battery of antibodies specific for various HLA-A antigens. Here, donor 1 shares HLA-A antigens recognized by antisera in wells 1 and 7 with the recipient, whereas donor 2 has none of HLA-A antigens in common with the recipient

Graft Donors and Recipients Are Typed for RBC and MHC Antigens

O May involve professional counselors/ psychotherapist

O Aimed at preventing / minimizing possible complication

O Need for adherence to post-op maintenance medications

O Regular follow-up thorough evaluation

O Life style modification; smoking, alcohol, sedentary life style, junks,

excessive salt ingestion.

COUNSELING

INFORMED CONSENT

Living Donor ; Education

Willingly not for any financial reason or under stress

Most undergo extensive screening – medical, psychological

Surgery and anesthetic complications outline to patients

DECEASED DONOR Some Factors influencing refusal to consent by relatives;

non-acceptance of brain death.

A delay in funeral

Lack of consensus within family members

Fear of social criticism

Dissatisfaction with the hospital staff

Various Superstitions & Religious beliefs

INFORMED CONSENT

RECIPIENT

Nature of disease and the need for transplant

Outcome and complications

Need for compliance to immunosuppressive therapy

Other available options

OPTIMIZATION OF RECIPIENT

Correction of derangements, getting patient ready for surgery

Correction of anemia

Uremia

Dehydration

Treatment of infection

Central line

Urethral catheter

Loading dose immunosuppression 12hr pre-op

Prophylactic antibiotics

PRINCIPLES

INTRA-OPERATIVE

Organ procurement and preservation

LIVING DONORsa. Strict asepsis and hemostasis

b. Adequate exposure

c. Removal of the organ

d. Preservation

Preservation

After removal, the

organ is flushed with chilled

organ preservation solution

e.g.

University of Wisconsin(UW),

Eurocolins,

HTK,

Celsior,

Custodiol,

Citrate/Marshall solutions

g. Organ packaging

NONHEART-BEATING KIDNEY DONATION

Initiation of preservation in situ- for DCD donors- donation after circulatory death donors

h. Transplantation/vascular reconstruction

Warm ischemic time ; time an organ remains at body temperature

between which the blood supply is cut off before cold perfusion. (within

30min)

Cold ischemic time ; the time between the chilling of the organ, after

blood supply has been cut off and the time it is warmed by reconnection

Maximum and optimal cold storage times (approximate)Organ Optimal (hours ) Safe maximum(hours) Kidney < 24 48Liver < 12 24Pancreas < 10 24Small intestine < 4 8Heart < 3 6Lung < 3 8

PRINCIPLES

Post-operativePost-operative assessment

Clinical – vital signs; fever, tachychardia, hypertension, pain at site of

transplant, pedal edema (compression of external iliac vein), decrease urine

volume- features of hyperacute rejection

Investigations ; U/Scr USG- increase in size, pelvicalyceal dilation

Biopsy; mononuclear infiltrates, fibrinoid necrosis, interstitial

haemorrhage. Others

Maintenance immunosuppression, DVT prophylaxis

Treatment of infection , Regular follow up

IMMUNOSUPPRESSION

The principles are the same for all type of organ transplant; maximize graft

protection and minimize side effect.

The agents used to prevent rejection act predominantly on T cells.

The need for immunosuppression is highest in the first 3 month but indefinite

treatment is needed

It increase the risk of infection and malignancy.

AGENT MODE OF ACTION SIDE FFECT

CALCINEURINE INHIBITORSCyclosporineTacrolimus

Block IL-2 gene transcription

Nephrotoxicity, hypertension,dyslipidaemia, hirsutism, gingival hyperplasia, neurotoxicity and diabetes

AZATHIOPRINE Prevents lymphocyteproliferation

Leucopenia, thrombocytopenia,hepatotoxicity, gastrointestinalsymptoms

MYCOPHENOLIC ACID DERIVATIVES eg MMF –Mycofenolate mofetil

Prevents lymphocyteproliferation

Leucopenia, thrombocytopenia,gastrointestinal symptoms

CORTICOSTEROIDS Widespread anti-inflammatoryeffects

Hypertension, dyslipidaemia, diabetes,osteoporosis, avascular necrosis,cushingoid appearance

mTOR-inhibitors Sirolimus, Everolimus

Blocks IL-2 receptor signaltransduction

Thrombocytopenia, dyslipidaemia,pneumonitis, impaired woundhealing

AGENT MODE OF ACTION SIDE EFFECT

ANTIBODY THERAPIES a. OKT3 monoclonal

antibodyb. Anti-CD25

monoclonal antibody

c. Polyclonal antibody [antilymphocyte globulin (ALG) or anti-lymphocyte serum (ALS)]

Depletion and blockade of TCellsTargets activated T cells

Depletion and blockade oflymphocytes

a. Cytokine release syndrome, pulmonary oedema, leucopenia

b. None describedc. Leucopenia,

thrombocytopenia

REGIMENS

Immunosuppressive agents are given as

Induction; early post-op period

Maintenance ; given for life

Rescue agents ; to reverse acute rejection

Induction regimen (most currently used )

CNI + anti CD 25 monoclonal antibody

Triple therapy ; CNI, anti-proliferative agent (MMF) and steroids

Dual therapy ; CNI + MMF or steroids

Polyclonal antibody (ALG/ALS)

Maintenance ; mTOR- inhibitors (specially in kidney transplant because they provide a

non-nephrotoxic alternative to CNI)

Multidrug therapy ; steroids, anti-proliferatives, CNIs.

Acute Rejection; Polyclonal antibody combine with induction regimen- quadruple therapy.

COMPLICATIONS OF IMMUNOSUPPRESSION

INFECTIONS; high risk of opportunistic infections

o Bacterial : common during first month after transplantation

Community acquired infections

Wound infection

UTI (catheter related)

Tuberculosis


o Viral ; highest in the first six month

• CMV infection; may presents as pneumonia, gastrointestinal disease,

hepatitis, retinitis, encephalitis

• Herpes simplex virus (HSV) ; muco-cuteneous lesions sometimes

around the genitalia

• BK-virus; graft dysfunction

• Herpes zoster infection; chicken pox

o Fungal ; pneumocystis jiroveci (carinii), candidiasis, aspergillosis

o Parasitic; strongiloides, leishmaniasis, toxoplasmosis


MALIGNANCYo Post transplant lymphoprolipherative disease (PTLPD); seen 1-3% of

kidney transplant with 50% mortality

o Squamous cell ca of the skin

o Basal cell ca and malignant melanoma are higher in transplant patient than the

general population

o 50% of transplant patient would develop skin malignancy in 20years

o Kaposi sarcoma; 300 fold increased risk

KIDNEY TRANSPLANT

Indications o End-stage renal disease

Causes : Glomerulonephritis;

Diabetic Nephropathy;

Hypertensive Nephrosclerosis;

Renal Vascular Disease;

Polycystic Disease;

Pyelonephritis;

Obstructive Uropathy;

Systemic Lupus Erythematosus;

Analgesic Nephropathy;

Metabolic disease (oxalosis, amyloid).

Irreversible GFR of less than 10 mL/min

serum creatinine level of greater than 8 mg/dl

O

Exclusion criteria for living donor

Exclusion Criteria for Recipient Drug abuse.

Morbid obesity. BMI >/= 35 Compliance

• S. phosphorus </= 6mg/dl

• Inter-dialysis wt gain (<5% dry wt for period of 3 month)

High risk of heart disease.

Cause of ESRD

• Focal segmental glomerulosclerosis

• Hemolytic uremic syndrome.

• 10 Oxalosis

Active Infection

Active malignancy

O DONOR NEPHRECTOMY

O DONOR BENCH SURGERY

O TRANSPLANTATION

OPERATIVES

Donor Nephrectomy

Open or Laparoscopic or Robotic.

Laparoscopic donor nephrectomy is the gold standard.

Open donor nephrectomy is via the 11th/12th rib cutting incision, and in fat

patient 10th rib cutting incision.

Extraperitoneal : avoid de-vascularizing ureter, sharp dissection, avoid

diathermy near vessels

Renal vasculature dissect flush to IVC/Aorta

Ligate lumbar veins posteriorly ± gonadal vein

Donor Kidney Bench Surgery

o The kidney is perfused with ice-cold preservative

o Iced saline is mashed into a slush and kidney immersed

o Extra veins ligated, accessory artery(ies) anastomosed together

o Kidney now ready for transplanting

PRESERVATIVESIschemia

Na pump is impaired

NaCl and water passively diffuse into the cell

Cellular swelling & NO-REFLOW phenomenon

Cellular K & Mg lost.

Ca + gained

Anaerobic glycolysis and Acidosis

Lysosomal enzymes activated

On reperfusion, Hypoxanthine a product of ATP

degradation is oxidized to xanthine and free

radicals causes further injury

ATP and Oxygen depletion

Patho-physiology

ATP-MgCl2

Ca+ channel blocker

Vaso-protective agents

Free radical scavenger

Lysosome stabilizer

(Methylprednisolone)

THE TRANSPLANT

o Right donor kidney to left recipient site and vice versa

o Gibson’s incision; Curvilinear incision 2 cm above the inguinal

ligament, from midline to just above the anterior Sup. Iliac Spine

o End to side venous anastomosis 5/0 prolene

o End to end arterial anastomosis 5/0 prolene

o Implant ureter to bladder

Recipient Preparation

o Antibiotic administered just before surgery.

o Immunosuppression started just before or during surgery.

o Before temporary vascular occlusion HEPARIN is given I/V to recipient.

Indication for pre-transplant Nephrectomy

o Renal stone not cleared.

o Polycystic symptomatic (infected) kidney.

o Persistent anti glomerular basement membrane antibody.

o Significant protienuria.

o Recurrent pyelonephritis.

o Grade 4/5 Hydronephrosis

Extra-peritoneal approach in either iliac fossa. Renal artery is anastomosed end-to-end to the internal iliac artery or end-to-side to the external iliac artery. Renal vein is sutured end to side to external iliac vein. After revascularization, the ureter is implanted into the side wall of the bladder

COMPLICATIONS

TECHNICAL Vascular hemorrhage; Vascular thrombosis 10-20%, within 2-3

days→ technical, 2/12→rejection, most are lost: ↓urine output, ↑creatine

Urological ; infection, fistula, obstruction Wound infection

RENAL Acute tubula necrosis Cortical necrosis Lymphocele Graft rupture Recurrent glomerulo-nephritis

Outcome Patient survival after deceased donor renal transplantation is >90% at 1 year and

> 80% at 5 years.

Graft survival is around90% at 1 year and 75% at 5 years. Graft survival after a

second transplant is only marginally worse than after a first graft.

After living-related kidney transplantation, overall graft survival is around 95% at 1

year and 85% at 5 years.

The half-life of grafts obtained from living donors is longer than that of cadaveric

grafts:

• deceased donor grafts : 13 years;

• living unrelated grafts : 14 years;

• living haplo-identical grafts : 15 years;

• living identical sibling grafts : 27 years

ETHICAL CONSIDERATION

INTERNATIONAL PERSPECTIVES ON THE ETHICS AND

REGULATION OF HUMAN CELL AND TISSUE TRANSPLANTATION o Consent for removal of human cells and tissues

o Confidentiality of donor data

o Unpaid donation

o Fair procurement of cells and tissues

o Stewardship for donated cells and tissues

o Quality and safety of HC/HT procurement and processing

o Fair distribution of processed cells and tissues

o Consent for HC/HT transplantation

Future trend

Genetic engineering – Cloning

Newer specific Immuno-suppresive therapy

CONCLUSION

Organ transplant is a successive therapeutic

option for treatment of end-stage organ disease.

Success depends on improved surgical technique,

immunosuppression, organ preservation and

follow-up .

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edition CRC press Taylor and Francis group. 2013O E.A Badoe et al, “Principles and Practice of surgery

including pathology in the tropics” 4th edition, Assembly of God Literature Center ltd, 2009

O M.A.R Al-Fallouji; “Postgraduate Surgery the candidate guide”. 2nd Edition. Rced Educational and Professional Pub. Ltd 1998

O Sabiston texbook of surgery. 18th edition.2007O Andrew C et al “Operative urology at the cleveland

clinic” 2nd edition. 2006.O Campbell-walsh urology.