diff --git a/samples/langchain_on_vertexai/clean_up.py b/samples/langchain_on_vertexai/clean_up.py
index 45e57ae5..42c3866a 100644
--- a/samples/langchain_on_vertexai/clean_up.py
+++ b/samples/langchain_on_vertexai/clean_up.py
@@ -13,6 +13,7 @@
 # limitations under the License.
 import asyncio
 import os
+from typing import Any, Coroutine
 
 from config import (
     CHAT_TABLE_NAME,
@@ -32,6 +33,15 @@
 TEST_NAME = os.getenv("DISPLAY_NAME")
 
 
+async def run_on_background(engine: PostgresEngine, coro: Coroutine) -> Any:
+    """Runs a coroutine on the engine's background loop."""
+    if engine._default_loop:
+        return await asyncio.wrap_future(
+            asyncio.run_coroutine_threadsafe(coro, engine._default_loop)
+        )
+    return await coro
+
+
 async def delete_tables():
     engine = await PostgresEngine.afrom_instance(
         PROJECT_ID,
@@ -42,12 +52,14 @@ async def delete_tables():
         password=PASSWORD,
     )
 
-    async with engine._pool.connect() as conn:
-        await conn.execute(text("COMMIT"))
-        await conn.execute(text(f"DROP TABLE IF EXISTS {TABLE_NAME}"))
-        await conn.execute(text(f"DROP TABLE IF EXISTS {CHAT_TABLE_NAME}"))
+    async def _logic():
+        async with engine._pool.connect() as conn:
+            await conn.execute(text("COMMIT"))
+            await conn.execute(text(f"DROP TABLE IF EXISTS {TABLE_NAME}"))
+            await conn.execute(text(f"DROP TABLE IF EXISTS {CHAT_TABLE_NAME}"))
+
+    await run_on_background(engine, _logic())
     await engine.close()
-    await engine._connector.close_async()
 
 
 def delete_engines():
diff --git a/samples/langchain_on_vertexai/create_embeddings.py b/samples/langchain_on_vertexai/create_embeddings.py
index 105a86df..370d8262 100644
--- a/samples/langchain_on_vertexai/create_embeddings.py
+++ b/samples/langchain_on_vertexai/create_embeddings.py
@@ -13,6 +13,7 @@
 # limitations under the License.
 import asyncio
 import uuid
+from typing import Any, Coroutine
 
 from config import (
     CHAT_TABLE_NAME,
@@ -32,6 +33,15 @@
 from langchain_google_cloud_sql_pg import PostgresEngine, PostgresVectorStore
 
 
+async def run_on_background(engine: PostgresEngine, coro: Coroutine) -> Any:
+    """Runs a coroutine on the engine's background loop."""
+    if engine._default_loop:
+        return await asyncio.wrap_future(
+            asyncio.run_coroutine_threadsafe(coro, engine._default_loop)
+        )
+    return await coro
+
+
 async def create_databases():
     engine = await PostgresEngine.afrom_instance(
         PROJECT_ID,
@@ -41,10 +51,14 @@ async def create_databases():
         user=USER,
         password=PASSWORD,
     )
-    async with engine._pool.connect() as conn:
-        await conn.execute(text("COMMIT"))
-        await conn.execute(text(f'DROP DATABASE IF EXISTS "{DATABASE}"'))
-        await conn.execute(text(f'CREATE DATABASE "{DATABASE}"'))
+
+    async def _logic():
+        async with engine._pool.connect() as conn:
+            await conn.execute(text("COMMIT"))
+            await conn.execute(text(f'DROP DATABASE IF EXISTS "{DATABASE}"'))
+            await conn.execute(text(f'CREATE DATABASE "{DATABASE}"'))
+
+    await run_on_background(engine, _logic())
     await engine.close()
 
 
@@ -95,7 +109,7 @@ async def grant_select(engine):
         engine,
         table_name=TABLE_NAME,
         embedding_service=VertexAIEmbeddings(
-            model_name="textembedding-gecko@latest", project=PROJECT_ID
+            model_name="text-embedding-005", project=PROJECT_ID
         ),
     )
 
diff --git a/samples/langchain_on_vertexai/prebuilt_langchain_agent_template.py b/samples/langchain_on_vertexai/prebuilt_langchain_agent_template.py
index 472b9da9..9e492783 100644
--- a/samples/langchain_on_vertexai/prebuilt_langchain_agent_template.py
+++ b/samples/langchain_on_vertexai/prebuilt_langchain_agent_template.py
@@ -65,7 +65,7 @@ def similarity_search(query: str) -> list[Document]:
         engine,
         table_name=TABLE_NAME,
         embedding_service=VertexAIEmbeddings(
-            model_name="textembedding-gecko@latest", project=PROJECT_ID
+            model_name="text-embedding-005", project=PROJECT_ID
         ),
     )
     retriever = vector_store.as_retriever()
diff --git a/samples/langchain_on_vertexai/requirements.txt b/samples/langchain_on_vertexai/requirements.txt
index f841a4c3..064bf76a 100644
--- a/samples/langchain_on_vertexai/requirements.txt
+++ b/samples/langchain_on_vertexai/requirements.txt
@@ -1,4 +1,4 @@
-google-cloud-aiplatform[reasoningengine,langchain]==1.120.0
+google-cloud-aiplatform[reasoningengine,langchain]==1.121.0
 google-cloud-resource-manager==1.14.2
 langchain-community==0.3.31
 langchain-google-cloud-sql-pg==0.14.1
diff --git a/samples/langchain_on_vertexai/retriever_agent_with_history_template.py b/samples/langchain_on_vertexai/retriever_agent_with_history_template.py
index 7d8a520e..2867d041 100644
--- a/samples/langchain_on_vertexai/retriever_agent_with_history_template.py
+++ b/samples/langchain_on_vertexai/retriever_agent_with_history_template.py
@@ -91,7 +91,7 @@ def set_up(self):
             engine,
             table_name=self.table,
             embedding_service=VertexAIEmbeddings(
-                model_name="textembedding-gecko@latest", project=self.project
+                model_name="text-embedding-005", project=self.project
             ),
         )
         retriever = vector_store.as_retriever()
diff --git a/samples/langchain_on_vertexai/retriever_chain_template.py b/samples/langchain_on_vertexai/retriever_chain_template.py
index d05780c3..8abfbb21 100644
--- a/samples/langchain_on_vertexai/retriever_chain_template.py
+++ b/samples/langchain_on_vertexai/retriever_chain_template.py
@@ -97,7 +97,7 @@ def set_up(self):
             engine,
             table_name=self.table,
             embedding_service=VertexAIEmbeddings(
-                model_name="textembedding-gecko@latest", project=self.project
+                model_name="text-embedding-005", project=self.project
             ),
         )
         retriever = vector_store.as_retriever()