Pancreas and islet cell transplantation

Indications & Selection - Sweet New Glands

• Primary Indication: Type 1 Diabetes (T1DM) with severe, life-threatening complications, often alongside renal failure.
• Main Categories:
  • Simultaneous Pancreas-Kidney (SPK): Most common. For T1DM with end-stage renal disease (ESRD).
  • Pancreas After Kidney (PAK): For T1DM patients with a prior kidney transplant.
  • Pancreas Transplant Alone (PTA): For T1DM with severe metabolic instability (e.g., hypoglycemic unawareness) but adequate renal function.
• Core Criteria: C-peptide negative, adequate cardiac reserve.

⭐ The most common procedure is the Simultaneous Pancreas-Kidney (SPK) transplant for T1DM patients who also require a kidney.

Surgical Techniques - Plumbing the Pancreas

• Goal: Anastomose donor pancreas vessels & manage exocrine drainage.
• Vascular Anastomosis:
  • Arterial Supply: Donor iliac artery Y-graft (supplying splenic & superior mesenteric arteries) connected to recipient's iliac artery.
  • Venous Drainage: Donor portal vein connected to recipient's superior mesenteric or iliac vein.

• Exocrine Drainage:
  • Enteric (most common): Donor duodenum to recipient jejunum.
  • Bladder (historic): Donor duodenum to recipient bladder; allows urine amylase monitoring for rejection.

⭐ The vast majority of transplants now use enteric drainage due to lower rates of metabolic acidosis, reflux pancreatitis, and UTIs.

Immunosuppression - Rejection Rejection!

• Induction & Maintenance: Typically a triple-drug regimen.
  • Calcineurin Inhibitor (e.g., Tacrolimus)
  • Antimetabolite (e.g., Mycophenolate Mofetil)
  • Corticosteroids
• Acute Rejection: Suspect with unexplained hyperglycemia & ↑ serum amylase/lipase. Biopsy is gold standard for diagnosis.
• Treatment: Initially with steroid boluses. Use lymphocyte-depleting agents (e.g., ATG) for steroid-resistant cases.

⭐ Venous thrombosis is the most common non-immunologic cause of early graft loss.

Complications - Transplant Troubles

• Early Graft Loss:
  • Vascular Thrombosis: Venous > Arterial. Often requires graft pancreatectomy. A leading cause of technical failure.
• Rejection:
  • Acute Cellular (ACR): T-cell mediated. Dx: Biopsy. Tx: Steroids, anti-T-cell antibodies.
  • Chronic: Antibody-mediated, leads to fibrosis/vasculopathy.
• Infections (immunosuppression-related):
  • CMV, Polyomavirus (BK virus), fungal infections.
• Surgical/Anastomotic:
  • Leaks: From enteric or bladder drainage sites.
  • Graft Pancreatitis: Presents with ↑ serum amylase/lipase.

⭐ Venous thrombosis is the leading cause of non-immunologic graft failure in the early post-operative period.

Islet Cell Transplant - Just the Cells, Ma'am

• Concept: Minimally invasive procedure where islets are isolated from a donor pancreas and infused into the recipient's portal vein.
• Primary Indication: Type 1 diabetes with severe hypoglycemia unawareness and glycemic lability, despite optimal medical management.
• Mechanism: Islets lodge in the liver sinusoids, engraft, and secrete insulin directly into the portal circulation.

⭐ Exam Favorite: A major limitation is the need for a large islet mass, often requiring cells from 2 or more donor pancreata for a single recipient to achieve insulin independence.

High‑Yield Points - ⚡ Biggest Takeaways

• SPK transplant (Simultaneous Pancreas-Kidney) is the most common procedure for Type 1 diabetes with ESRD.
• Vascular thrombosis is the leading cause of early graft loss, especially in the first 24-48 hours.
• Enteric drainage is now preferred over bladder drainage to avoid metabolic acidosis and urologic complications.
• Acute rejection presents with rising serum amylase/lipase and hyperglycemia; biopsy is diagnostic.
• Lifelong triple-drug immunosuppression is mandatory, increasing risk for opportunistic infections like CMV.
• Islet cell transplantation is less invasive but offers lower rates of long-term insulin independence.