Hematopoietic stem cell transplant (Harrison based)

1. HAEMATOPOIETIC
STEM CELL
TRANSPLANTATION
DR. NIRMALYA MALLICK
3RD YEAR PGT
DEPT OF GENERAL MEDICINE
RGKMCH

2. What is a stem cell ?
• Stem cells are undifferentiated pluripotent precursors that are able to transform
into mature cells with specialized function.
• Stem cell pool is only 100,000 and if stem cell is damaged, a person can survive
only 2 to 4 weeks in absence of extraordinary support measures.
• Stem cells can undergo Self renewal and differentiation.
• In bone marrow hematopoietic stem cells are present in two niche areas.
1. Endosteal niche
2. Perivascular niche
These niche areas act as both a nutritive and constraining home for hematopoietic
stem cells.

3. • Hematopoietic stem cells anchor to these niche by means of receptors ( CXCR
4, VCAM 1) present on stem cells that interact with ligands ( CXCL12, VLA 4)
present on mesenchymal cells of bone marrow.
• G-CSF and Plerixafor target these interactions to mobilize stem cells from bone
marrow to peripheral blood.

4. HEMATOPOIETIC STEM CELL
TRANSPLANTATION

5. • Hematopoietic cell transplantation is used to treat patients with both abnormal
but nonmalignant lymphohematopoietic system by replacing it with one from a
normal donor and malignancy by allowing the administration of higher doses of
myelosuppressive therapy than would otherwise be possible.
• The Center for International Blood and Marrow Transplant Research estimates
that worldwide about 100,000 transplants were performed in 2020.
• Transplantation of a small percentage of a donor’s bone marrow volume
regularly results in complete and sustained replacement of the recipient’s entire
lymphohematopoietic system, including all red cells, granulocytes, B and T
lymphocytes, and platelets, as well as the fixed macrophage population, like
Kupffer cells of the liver, pulmonary alveolar macrophages etc.

6. How the Hematopoietic stem cell transplantation has been made
clinically feasible ?
Hematopoietic stem cells has some special features:
1. Remarkable regenerative property.
2. Ability to home to marrow space following IV injection :
a) CXCL12- CXCR4 interaction
b) Selectin ( E & L- Selectin) Integrin ( VLA-4 ) interaction.
3. Ability to be cryopreserved.

7. Categories of Hematopoietic stem cell transplantation
Hematopoietic stem cell transplantation can be described by 2 means
1. According to relationship between patient and donor.
a) Syngeneic transplantation
b) Autologous transplantation
c) Allogenic transplantation
2. According to anatomic source of stem cell.

8. Syngeneic transplantation :
• Between identical twins.
• No risk of GVHD yet no risk of stem cells contaminated with tumour cells.
• GVT effect is absent hence post transplant relapse rate is higher.
Autologous transplantation :
• It involves removal, storage of patient’s own stem cells and post
myeloablative therapy reinfusion of those stem cells.
• No risk of GVHD or graft rejection.
• No GVT effect & high risk of stem cells being contaminated with tumour
cells. So,high relapse rate.

9. Allogenic transplantation :
• Donor and recipient are not genetically identical.
• High risk of GVHD and Graft rejection.
• GVT effect is seen.

10. Human leukocyte antigen (HLA) matching and Allogenic transplant
• HLA molecules are encoded by MHC complex genes.
• If donor and recipient are not HLA matched, T cells of one individual
strongly reacts to mismatched HLA of the second.
• HLA genes of major relevance are HLA- A, -B, -C, -D.
• Incidence of graft rejection and GVHD increases with no. of mismatched
HLA antigen.
• Survival following HLA matched unrelated donor transplant and HLA
matched sibling transplant are essentially the same due to improvement
in HLA typing and supportive care.

11. Categories of Hematopoietic stem cell transplantation
Hematopoietic stem cell transplantation can be described by 2 means
1. According to relationship between patient and donor.
a) Syngeneic transplantation
b) Autologous transplantation
c) Allogenic transplantation
2. According to anatomic source of stem cell.
a) Bone marrow graft
b) Peripheral blood stem cell graft
c) Cord blood graft

12. Bone marrow graft :
• Aspirated from posterior and anterior iliac crest.
• 10 -15 ml/kg volume of bone marrow is collected.
Cord blood graft :
• Umbilical cord contains high concentration of HSC.
• Peripheral count recovery takes longer time than that of BM transplant.
• Advantages: 1. Rapid availability of unrelated cord blood.
• 2. Decreased immune reactivity due to lower no of T cells in cord blood.
• The risk of graft failure and transplant related mortality are related to dose of cord
blood cells.
• Use of double cord transplant diminishes the risk of graft failure and early mortality.

13. Peripheral blood stem cell graft :
Hematopoietic stem cells circulate in the peripheral blood in very low
concentrations. Hence following steps are required.
• Donors are treated with granulocyte colony stimulating factor (G-CSF) for 4 to
5 days prior to collection day
• Stem cells are collected in one or two 4 hour leukapheresis sessions.
• Adequate number of stem cells (as measured by CD34) harvested.
Patients who fail to mobilize enough stem cells from marrow to peripheral blood
with G- CSF alone, the addition of Plerixafor (CXCR4 antagonist) may be useful.

14. Peripheral blood stem cell transplant versus bone marrow
transplant in allogenic transplantation
• Engraftment is faster in PBSC transplantation.
• Chronic GVHD is more in PBSC transplantation due to T cell contamination.
So, in case of unrelated matched donor, BM transplantation is favourable.

15. THE TRANSPLANT PREPARATIVE REGIMEN
• Reason: 1. To eradicate the patient’s underlying disease.
2. To immunosuppress the patient adequately to prevent graft
rejection in case of allogenic transplantation.
• The appropriate regimen therefore depends on the disease setting and graft
source.
For example,
1. In severe combined immunodeficiency (SCID) if the donor is a
histocompatible sibling, no treatment is needed because no host cells require
eradication and the patient is already too immune-incompetent to reject the
transplanted graft.

16. 2. For aplastic anemia, there is no large population of cells to eradicate, only
immunosuppression is adequate.
Regimen used: High dose cyclophosphamide plus Antithymocyte globulin.
3. In thalassemia and Sickle cell anemia, there is hyperplastic host
hematopoiesis.
Regimen used: Cyclophosphamide plus high dose Busulfan (for myelosuppression)
4. In malignant diseases: Various regimen are used. Most of them use high
activity against tumor in question at conventional doses with myelosuppression
as their dose limiting toxicity.
Drugs used : Busulfan, cyclophosphamide, melphalan, etoposide, total body
irradiation in various combinations

17. Newer concept of Preparative conditioning
Although high dose treatment regimen were used initially, realization of graft versus
tumor (GVT) effect warrened use of following alternative regimens.
1. Nonmyeloablative regimen: Only transient myelosuppression is seen if no
transplantation is performed.
Fludarabine plus total body irradiation used.
2. Reduced intensity regimen: It causes significant but not necessarily fatal
myelosuppression in the absence of transplantation
Fludarabine plus melphalan used.
But relapse rates are higher in these regimens hence they are used if patient can
not tolerate the Myeloablative conditioning or has significant comorbidities.

18. ENGRAFTMENT AND IMMUNE RECONSTITUTION
What is Engraftment?
• Neutrophils engraftment and platelet engraftment
• ANC > 500 for at least 3 days,1st day of these 3 days is called 'Day of
neutrophil engraftment’
• Platelet count >20000 for at least 7 days without transfusion support, 1st day of
these 7 days is called 'Day of platelet engraftment'.

19. • Rate of engraftment depends upon source of stem cell.
 PBSC graft-2 weeks
 BM graft- 3 weeks
 Cord blood graft- 4 weeks
• Use of post transplant myeloid growth factor accelerates recovery by 3-5 days.

20. • Components of innate immunity ( granulocytes and macrophages) recover rapidly
following transplant.
• Adaptive immunity takes longer time to recover.
 T cells- for initial months CD8+ T cells with limited receptoire are there. Later,
donor derived CD4+ and CD8+ T cells becomes dominant with diverse T-cell
repertoire.
 B cells- Recovers 6 months after autologous HSCT and 9 months after allogeneic
HSCT.
• In general, immunity recovery occurs more rapidly after autologous HSCT.
• Method of documentation of engraftment:
1. Short tandem repeat polymorphism
2. fluorescence in situ hybridization (FISH) of sex chromosomes. ( In sex
mismatched transplant)

21. COMPLICATIONS FOLLOWING
HEMATOPOIETIC
CELL TRANSPLANTATION

22. • Early direct chemo radiotoxicity
 Nausea, vomiting, mild skin erythema
 Hair loss
 Profound pancytopenia
 Hemorrhagic cystitis - Due to use of high dose cyclophosphamide.
Treatment- bladder irrigation, MESNA
 Oral mucositis- typically develops 5–7 days after transplant.
Treatment- narcotic analgesia, Palifermin (keratinocyte growth factor) can
shorten duration.

23.  Sinusoidal obstruction syndrome (SOS) of liver
Due to direct cytotoxic injury to hepatic-venular and sinusoidal
endothelium, with subsequent deposition of fibrin and the development of a
hypercoagulable state.
- Peak incidence at day 16 post transplant.
- Mortality-30%
- C/F- Tender hepatomegaly, ascites, jaundice
- Treatment- Defibrotide ( a polydeoxyribonucleotide)
 Diffuse interstitial pneumonia- Treatment- High-dose glucocorticoids.

24.  Transplant associated thrombotic microangiopathy
- Characterized by presence of schistocytes on peripheral smear, elevated
lactate dehydrogenase, thrombocytopenia, and acute kidney injury.
- Calcineurin inhibitors are thought to contribute to the pathogenesis.
- Treatment- Changing immunosuppressive regimens
Eculizumab may be used.

25. • Late Direct Chemoradiotoxicities
 Pulmonary complications
Two categories of chronic pulmonary disease.
A. Cryptologic organizing pneumonia
- A restrictive lung disease, presents with dry cough and SOB.
- Treatment- responds well to corticosteroids. (entirely reversible)
B. Bronchiolitis obliterans-
- An obstructive lung disease, presents with cough and progressive
dyspnea.
- Usually associated with chronic GVHD.
- Treatment- Responds somewhat to increasing immunosupression but
complete reversal is uncommon.

26.  Decreased growth velocity in children and delayed development of secondary sex
characteristics- Most men become azoospermic, and most postpubertal women
develop ovarian failure.
 Cataracts and Aseptic necrosis of the femoral head- both are due to chronic
glucocorticoid therapy.

27.  Graft failure
Characterized by non return of marrow function following transplant or it's
loss after a brief period of engraftment.
• Following autologous transplantation, can be due to
- Inadequate stem cell transplantation
- Damage during storage
- Exposure of the patient to myelotoxic agents after transplant
- Infections with cytomegalovirus (CMV) or human herpesvirus type 6.
• Following allogenic transplantation, can be due to
- Graft rejection by immunocompetent cells of recipient
- Poor engraftment due to presence of pretransplant donor-specific HLA
antibodies in the patient.
• Treatment- Removal of all myelotoxic agents and short trial of a myeloid growth
factor.

28.  Graft Versus Host Disease
It is caused by immune cells transplanted with the stem cells or developing
from them that react against the patient following allogeneic transplantation.
Types : a. Acute GVHD
b. Chronic GVHD
c. Late onset acute GVHD

29. Acute GVHD
- Occurs within 3 months.
- Risk factors- Mismatched or unrelated donors, Older patients, Multiparous
female donors etc.
- Clinical features: maculopapular rash, persistent anorexia or diarrhea, or
both, liver disease with increased liver enzymes.
- Grades- I to IV. Grade I shows mild symptoms and no change in survival.
But grade II to IV associated with serious symptoms and poor survival rate.
- Treatment – Prednisone. If response is inadequate, oral JAK2 inhibitor
ruxolitinib can be tried.
- Prophylaxis- CNI + MTX/ MMF +/- ATG

30. Chronic GVHD
- Occurs 3 months to 2 years post transplant.
- Risk factors- older patients, use of peripheral blood stem cells, recipients
of mismatched or unrelated stem cells, previous episode of acute GVHD.
- Clinical features: It resembles an autoimmune disorder with malar rash,
sicca syndrome, arthritis etc.
- Treatment: Mild chronic GVHD- local therapies.
Severe disease- Systemic therapy with prednisone alone or in
combination with Cyclosporine.
Late onset acute GVHD
- It is acute GVHD after 3 months.
- It shows clinical features of both acute and chronic GVHD also called
overlap syndrome.

32.  Infections
Posttransplant patients, particularly recipients of allogeneic transplantation
are at great risk of developing infections due to various microbes.

33. Treatment
• Bacterial infections- Levofloxacin
• Fungal infections- Fluconazole
Voriconazole, posaconazole (against mold and invasive
fungal infection)
Cotrimoxazole (against Pneumocystis jirovecii).
• Viral infections- HSV, VZV – Acyclovir
CMV- Letermovir (Prophylaxis)
Ganciclovir, Foscarnet (Treatment)
Influenza- Oseltamivir
RSV- Ribavirin (inhaled)

34. USES OF HEMATOPOIETIC
STEM CELL
TRANSPLANTATION

35. Nonmalignant diseases
• Immunodeficiency disorders : Severe combined immunodeficiency, Wiskott
Aldrich syndrome and Chédiak-Higashi syndrome.
• Aplastic anemia - curative in up to 90% cases aged <40 years.
• Haemoglobinopathies- Thalassemia major (80 to 90%), Sickle sell anemia.
• Storage disorders- Gaucher’s disease, Hurler’s syndrome, Hunter’s syndrome.
Malignant diseases
• Acute leukemia - AML & ALL
• Chronic leukemia - CML. CLL less studied.
• Myelodysplasia and myeloproliferative disorders
• Hodgkin's and Nonhodgkin's lymphoma
• Myeloma
• Neuroblastoma
• Pediatric sarcomas

36. THANK YOU