Fetal Pituitary Transplantation

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Fetal Pituitary Transplantation

• Viability and Functionality of Human Fetal
  Pituitary Cells Transplanted into
  Hypophysectomized Rats
• Reza Jarrahy, M.D.
• Hrayr K. Shahinian, M.D.
• Department of Surgery, Division of Skull Base
  Surgery
• Cedars-Sinai Medical Center
• Los Angeles, California

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Abstract

• Human fetal pituitary cells were transplanted
  into twenty three hypophysectomized rats via a
  transauricular approach. Baseline serum human
  growth hormone levels (hGH) were measured prior
  to intervention and then at one week intervals
  following transplantation. Rats receiving
  pituitary cell transplants demonstrated hGH
  levels that were maximal one week following
  transplantation and that gradually tapered off in
  the subsequent weeks. These results offer
  preliminary evidence that human fetal pituitary
  cells are able to survive and retain
  functionality after transplantation into rats.

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Background

• Pituitary transplant models historical
  perspectives
• Early work design
• species rodent (isograft/homograft/allograft)
• substrate neonatal and adult rodent pituitary
  tissue
• site renal, ocular, intracerebral (immunologic
  privilege thalamus ventricles corpus
  callosum temporal lobe)
• endpoints end organ weights histology

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Background

• Pituitary transplant models historical
  perspectives
• Early work outcomes
• pituitary function could be restored to
  hypophysectomized rats following transplantation
  of rat pituitary gland tissue
• most complete restitution seen in transplants to
  the median eminence (hypophysiotropic area)

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Background

• Pituitary transplant models historical
  perspectives
• Later work design
• species rodent xenografts (mouse pituitary to
  rat) (human striatum to rat)
• substrate fetal tissue cell cultures
• site median eminence
• endpoints serum hormone levels
  immunohistochemistry electron microscopy

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Background

• On substrate fetal tissues
• less immunogenic
• durable grafts
• There is no question that fetal tissue is
  superior to adult tissue as a source of graft
  material both because of its resistance to trauma
  and anoxia and because of its ability to
  proliferate. Fetal tissue may also elaborate a
  variety of trophic factors that may be beneficial
  to the host.
• Tulipan N Brain transplants. Neur Clin
  19886405-420.

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Background

• On substrate cell culture
• less immunogenic
• durable grafts
• Theoretical consideration regarding diffusion of
  nutrients to the center of grafts and development
  of a new blood supply render a theoretical
  advantage to using suspensions of tissue in which
  most cells are bathed in nutrient medium prior to
  transplantation In addition, it is known that
  cultured cells often lose their
  histocompatibility antigenicity and might
  therefore not be prone to rejection.

--Tulipan N Brain transplants. Neur Clin
19886405-420.
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Background

• Pituitary transplant models historical
  perspectives
• Later work outcomes
• Research into CNS transplantation has documented
  the ability of transplanted CNS tissues to
  survive, develop processes, elongate, organize
  into anatomically correct configurations, and
  establish electrophysiologically and secretorily
  functional synaptic connections with host tissue.

--Wilberger JE Transplantation of Central
Nervous Tissue. Neurosurgery 19831390-94.
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Background

• Pituitary transplant models historical
  perspectives
• Later work outcomes
• The pituitary gland itself may be transplanted
  to the median eminence of hypophysectomized rats
  with survival of pituitary tissue and resultant
  correction of hormonal abnormalities.
• Tulipan N Brain transplants. Neur Clin
  19886405-420.

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Background

• Pituitary transplant models historical
  perspectives
• Later work outcomes
• reaffirmation of earlier studies with more
  conclusive evidence
• documentation of successful inter-species human
  to rat CNS transplants (Parkinsonian models)
• successful use of fetal tissue

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Central question

• Can pituitary function be reconstituted in
  hypophysectomized rats after transplantation of
  human fetal pituitary cells?

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Method

• Species (recipient)
• Harlan/Sprague Dawley male hypophysectomized rats
• age 20 weeks weight 170-240 g
• Substrate
• human fetal pituitary cell culture
• derived from fetuses of 20 week gestation
• Site
• transauricular approach to medial basal
  hypothalamus
• Endpoints
• serum levels of human hormone (human GH, ACTH)
• endocrine organ histology

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Method
human pituitary cell suspension
hypophysectomized rat
serum hGH
serum hACTH
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Results hormone levels
serum hGH (ng/ml)
specimen
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Results hormone levels
serum hACTH (pg/ml)
rodent ACTH
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Results hormone levels
serum hACTH (pg/ml)
specimen
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Results histology

• In animals 1, 2, 3, and 5 (recent data), the
  endocrine glands were normal and did not exhibit
  histological signs of involution, indicating that
  they were exposed to the necessary quantities of
  adenohypophyseal hormones.

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Results histology

• In animals 4 and Control the abnormal histology
  of the testes, adrenals, and thyroids indicated
  that the endocrine glands were not under the
  influence of adenohypophyseal hormones.

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Conclusions

• Human fetal pituitary cells transplanted into the
  hypophysiotropic area of the hypophysectomized
  rat can remain viable and retain secretory
  function

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Conclusions

• Human fetal pituitary cells transplanted into the
  hypophysiotropic area of the hypophysectomized
  rat may, at least partially, reconstitute a
  normal hypothalamic-pituitary-end organ axis and
  regulate normal maturation and function of
  endocrine organs (thyroid, adrenals, gonads)

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Future directives

• Series with larger numbers of animals (greater
  statistical power) and both hypox and normal
  controls (underway)
• Immunosuppressive therapy trials (underway)
• Refined transplantation method
• Histology of skull base/sella/cerebral tissue

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References

• Akalan N, et al Fetal pituitary transplants into
  the hypothalamic area of hypophysectomized rats.
  Surg Neurol 198830342-349.
• Asa S, Kovacs K Functional morphology of the
  human fetal pituitary. Pathol Ann
  198419275-315.
• Csernus V, Lengvari I, Halasz B Further studies
  on ACTH secretion from pituitary grafts in the
  hypophysiotropic area. Neuroendocrin
  19751718-26.
• Das GD, Hallas BH, Das KG Transplantation of
  brain tissue in the brain of rat. I. Growth
  characteristics of neocortical transplants from
  embryos of different ages. Am J Anat
  1980158135-145. Flament-Durand J Observations
  on pituitary transplants into the hypothalamus of
  the rat. Endocrinology 196577446-454.
• Falconi G, Rossi GL Transauricular
  hypophysectomy in rats and mice. Endocrinology
  196474301-303.

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References

• Frodl EM, et al Human embryonic dopamine neurons
  xenografted to the rat effects of
  cryoprecipitation and varying regional source of
  donor cells on transplant survival, morphology
  and function. Brain Res 1994647286-298.
• Geny C, et al Microglial chimaerism in human
  xenografts to the rat brain. Brain Res Bull
  199538383-391.
• Halasz B, Pupp L, Uhlarik S Hypophysiotropic
  area in the hypothalamus. J Endocrin
  196225147-154.
• Martini L, et al Functional and morphological
  observations on the rat pituitary grafted into
  the anterior chamber of the eye. J Endocrin
  195919164-173.
• Nikitovitch-Winer M, Everett JW Functional
  restitution of pituitary grafts re-transplanted
  from the kidney to the median eminence.
  Endocrinology 195863916-930.

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References

• Pundt LL Localization of dopamine receptors and
  associated mRNA in transplants of human fetal
  tissue in rodents with experimental Huntingtons
  Disease. Neurosci Res 199727305-315.
• Pundt LL, et al Organization and histochemical
  phenotype of human fetal cerebellar cells
  following transplantation into the cerebellum of
  nude mice. Cell Transplant 19976479-489.
• Scheinberg LC, Edelman FL, Levy WA Is the brain
  an immunologically privileged site? Arch Neurol
  196411248-264.
• Tulipan NB Brain transplants. Neur Clin
  19886405-420.
• Tulipan NB, Huang S, Allen GS Pituitary
  transplantation cyclosporine enables
  transplantation across a minor histocompatibility
  barrier. Neurosurgery 198618316-320.
• Wilberger JE Transplantation of Central Nervous
  Tissue. Neurosurgery 19831390-94.

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